• Journal of the Korean Society of Safety
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• v.21 no.4 s.76
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• pp.102-107
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• 2006

Construction accidents have not decreased in spite of much effort such as new work methods, education and research related to safety works. Specially, many fatal accidents happened in construction works which involve the apartment, building, school, church, hotel, hospital, bank work and the other works. These accidents are mainly caused by unanticipated risk factors. From these reasons, this study researched fatal accidents which happened in construction works during last 13 years($1992{\sim}2004$) and analyzed the input workers and a work period of construction work. According to the input workers and a work period, the results are as following. During 13years($1992{\sim}2004$), the fatal accidents, related to the construction work, were happened to the 1,977 cases. These results were occupied the 21.32% of the total industry accidents. According to the result of the construction, the fatal accident rate of a concrete form work was the highest rate of 16.24% (321 cases) and a temporary work, a steel frame work was the each rate of 12.39%(245 cases), 10.07%(199 cases). Comparing to other work types, the fatal accident rate of those three work types(concrete form work, temporary work, steel work) was represented highly. We surveyed input workers and work period of construction work site. From the result of survey, input workers of a concrete form work were occupied with 13,720. The risk rate of the work type, which was considered input workers and work period, was represented 0.3622(a steel frame work), 0.1142(a temporary work), 0.0782(a tower crane) and 0.0772(a concrete work).

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.1
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• pp.9-13
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• 2002

The objective of this study was to analyze and make comparison between the physical responses such as oxygen consumption rate, heart rate, and EMG-measurement for lifting tasks. Lifting activities with three different working frequencies(5, 8, 11 lifts/min) and two different weights(10, 20kg) for a lifting range(from floor to 76cm height) were studied. It was found that theme are positive correlations between the oxygen consumption rate and the EMG-measurements on the region of law back. Even though these physical responses were influenced by work weights and work frequency, it was found that the work frequency plays more important role in making muscle fatigue than the work weight. From these finding it is suggested that the work frequency should be considered as a more influencing factor than the work weight as long as the weight belongs to the permissible range based on the viewpoint of the biomechanical criterion for designing a job of manual materials handling tasks.

• Structural Engineering and Mechanics
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• v.58 no.4
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• pp.719-729
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• 2016

The main objective of the present paper is to study the effect of the yield criterion on the magnitude of the strain rate and plastic work rate intensity factors in axisymmetric flow of isotropic incompressible rigid perfectly plastic material by means of a problem permitting a closed-form solution. The boundary value problem consisting of the axisymmetric deformation of a plastic tube is solved. The outer surface of the tube contracts. The radius of the inner surface does not change. The material of the tube obeys quite a general yield criterion and its associated flow rule. The maximum friction law is assumed at the inner surface of the tube. Therefore, the velocity field is singular near this surface. In particular, the strain rate and plastic work rate intensity factors are derived from the solution. It is shown that the strain rate intensity factor does not depend on the yield criterion but the plastic work rate intensity factor does.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.9
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• pp.2792-2799
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• 1996

It was shown in the previous study that the numerically derived elastic work factor for CLS specimen was independent of fiber direction for a unidirectional case. Also, it was proposed the elastic work factor could be used to determine energy release rate from a single test record. In the present study, elastic work factor was derived from a simple beam theory to investigate its dependence on material property and geometric condition. Also, the elastic work factor of CLS specimen was applied experimentally to determine critical energy release rate in order to prove its validity determining critical energy release rate from a single specimen. For this purpose, critical energy release rate determined using the elastic work factor was compared with that determined by the compliance method. The results showed that while elastic work factor is affected by $t_2/t_1$ and $L_2/L_1$ it is independent of fiber angle for a unidirectional case. It was also found that critical energy release rates determined by both methods are comparable each other, thus elastic work factor approach can be used to determine energy release rate from a single test specimen.

• Medical Lasers
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• v.10 no.3
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• pp.153-160
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• 2021

Background and Objectives This study was conducted to investigate the change of total work and total work ratio for each set, peak heart rate during exercise, and blood lactate for each set during the 5-set bench press exercise at 75% one repetition maximum test (1-RM). Materials and Methods Seven men in their 20s with more than 6 months of experience doing resistance exercises were selected as subjects, and their 1-RM bench press was measured two weeks before the experiment and 75% 1-RM was measured one week before the experiment. In this study, total work was measured for each set, and heart rate was measured during rest and set-by-set exercise. Blood lactate was measured during rest time after each set. The raw data were analyzed by repeated one-way ANOVA. Results Total work and total work ratio decreased from 1 set to 4 sets (p < .05), p < .001), heart rate increased from stable at the start of exercise (p < .001) and decreased between 3 sets and 4 sets (p < .05). Blood lactate increased continuously up to 2 sets (p < .001, p < .01). Conclusion In conclusion, total work and heart rate decreased with muscle fatigue during exercise, and blood lactate continuously increased. The results of this study are expected to be useful references for constructing resistance exercise programs in the future.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.27 no.3
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• pp.90-96
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• 2004

The objective of this study was to develop a model for safe work load based on a physiological model of metabolic energy of manual material handling tasks. Fifteen male subjects voluntarily participated in this study. Lifting activities with four different weights, 0, 8, 16, 24kg, and four different working frequencies (2, 5, 8, 11 lifts/min) for a lifting range from floor to the knuckle height of 76cm were considered. Oxygen consumption rates and heart rates were measured during the performance of sixteen different lifting activities. Simplified predictive equations for estimating the oxygen consumption rate and the heart rate were developed. The oxygen consumption rate and the heart rate could be expressed as a function of task variables; frequency and the weight of the load, and a personal variable, body weight, and their interactions. The coefficients of determination ($r^2$) of the model were 0.9777 and 0.9784, respectively, for the oxygen consumption rate and the heart rate. The model of oxygen consumption rate was modified to estimate the work load for the given oxygen consumption rate. The overall absolute percent errors of the validation of this equation for work load with the original data set was 39.03%. The overall absolute percent errors were much larger than this for the two models based on the US population. The models for the oxygen consumption rate and for the work load developed in this study work better than the two models based on the US population. However, without considering the biomechanical approach, the developed model for the work load and the two US models are not recommended to estimate the work loads for low frequent lifting activities.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.115-118
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• 2004

In this study, amplitudes of turbulence excitation are obtained for selected tubes inside the KSNP SG and their normal work-rates are investigated to estimate the magnitude of fretting-wear. From the results of numerical calculation, row 40&41 tubes show the maximum work-rates. Up to this row number, the work-rates inside the row 41 have much larger values than those of outside tubes. This phenomenon reveals the particular central one which has larger normal work-rate than that of outside zone. It turns out that both of the higher local mode at the U-bend region and the larger value of effective mass in the central region Increase the normal work-rate enormously.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.641-642
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• 2006

The purpose of this work is to investigate the effect of work load on heart rate variability (HRV) which is widely used marker of the autonomic nervous system activity. Average heart rate, rating of perceived exertion, and the power spectrum of heart rate variability were investigated in seven healthy males during exercise at various work loads. The subjects were divided into two groups according to the average heart rate during exercise, group 1 with lower heart rate and group 2 with higher heart rate. HF component showed decrease followed by increase with workload. Accordingly, the LF/HF ratio showed increase followed by decrease with workload. The peak in LF/HF ratio of group 1 was at the lower workload than that of group 2.

• Journal of Biosystems Engineering
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• v.36 no.3
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• pp.223-230
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• 2011

Physiological signals such as body temperature, heart rate, blood pressure and heart rate variability and biomechanical workload for stress analysis were investigated during the cherry tomato harvesting work in a greenhouse. The skin temperatures raised $0.05^{\circ}C$/min, $0.03^{\circ}C$/ min, and $0.08^{\circ}C$/min in standing, stooping and squatting postures, respectively. Breath rate significantly increased from 18 to 28 breaths/min during the cherry tomato harvesting work. As the heart rate during the work ranged from about 72 to 110 beats/min (bpm), the cherry tomato harvesting work appeared to be a light intensity task of less than 110 bpm. The worker's average energy consumption rate in three positions during 43 min working time was 65.74 kcal (91 kcal/h in 70 kg). This was a light intensity of work, compared to 75 kcal/h in 70 kg of basic metabolic energy consumption rate of a worker with 70 kg weight; The maximum shear force on the disk (L5/ S1) due to static workload in the cherry tomato harvesting work was 446 N in the stooping posture, 321 N in the squatting posture and 287 N in the standing posture. Acute stress index expressed with the heart rate variability, increased parasympathetic activation up to about 70 while workers were doing most agricultural work in this study. This study provided a system to measure quantitatively workers' physiological change, kinematics and kinetic factors without any restrictions of space in the greenhouse works.

• Asia pacific journal of information systems
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• v.28 no.1
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• pp.1-18
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• 2018

Despite the increasing interest in the positive effects of smart-work, the introduction rate of domestic firms in Korea is lower than that of other developed countries. A gap also exists between the introduction of smart-work program and the actual use by workers. Thus, even if the smart-work program was introduced to firms, the actual usage rate of the program would still be lower than the introduction rate. Moreover, even if the program was initially used, evidence suggests that the usage rate tends to decrease rather than being used continuously. In this study, we intend to find out the mechanism by which the continuance intention of smart-work is formed. To achieve this objective, we established a research model based on literature on Information System (IS) continuance model and Information & Communication Technology (ICT) support. We also hypothesize that concerns about career disadvantage in the mechanism plays a negative role in the satisfaction of smart-work. To analyze the hypothesis empirically, we surveyed domestic workers who used smart-work. Our data analysis was based on 333 responses. We found that all paths were statistically significant, except for the direct effect of ICT support on perceived usefulness and the direct effect of perceived usefulness on smart-work continuance intention. The results of this study extend existing IS continuance model and suggest implications for practical smart-work implementation and improvement.