• Smart Structures and Systems
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• v.30 no.1
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• pp.107-119
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• 2022

Modal parameters are widely used in bridge damage detection, finite element model (FEM) updating and design optimization. However, the conventional modal identification approaches require large number of sensors, enormous data processing workload, but normally result in mode shapes with low accuracy. This paper proposes a modal identification method of time-varying vehicle-bridge system using a single sensor. Firstly, the essential physical relationship between the instantaneous frequency of the vehicle-bridge system and the bridge mode shapes are derived. Subsequently, based on the synchroextracting transform, the instantaneous frequency of the system is tracked through the dynamic response collected by a single sensor, and further the modal parameters are estimated by using the derived physical relationship. Then numerical and experimental examples are conducted to examine the feasibility and effectiveness of the proposed method. Finally, the modal parameters identified by the proposed method are applied in bridge FEM updating. The results manifest that the proposed method identifies the modal parameters with high accuracy via a single sensor, and can provide reliable data for the FEM updating.

• Journal of KIISE:Computer Systems and Theory
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• v.37 no.2
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• pp.90-102
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• 2010

Flash memory has been widely used as an important storage device for consumer electronics. For the flash memory-based storage systems, FTL (Flash Translation Layer) is used to handle the mapping between a logical page address and a physical page address. Especially, log buffer-based FTLs provide a good performance with small-sized mapping information. In designing the log buffer-based FTL, one important factor is to determine the mapping structure between data blocks and log blocks, called associativity. While previous works use static associativity fixed at the design time, we propose a new log block mapping scheme which adjusts associativity based on the run-time workload. Our proposed scheme improves the I/O performance about 5~16% compared to the static scheme by adjusting the associativity to provide the best performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1194-1201
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• 2003

Measurements of network traffic have shown that self-similarity is a ubiquitous phenomenon spanning across diverse network environments. We have advance the framework of multiple time scale congestion control and show its effectiveness at enhancing performance for fast TCP prototype control. In this paper, we extend the fast TCP prototype control framework to window-based congestion control, in particular, TCP. This is performed by interfacing TCP with a large time scale control module which adjusts the aggressiveness of bandwidth consumption behavior exhibited by TCP as a function of "large time scale" network state. i.e., conformation that exceeds the horizon of the feedback loop as determined by RTT. Performance evaluation of fast TCP prototype is facilitated by a simulation bench-mark environment which is based on physical modeling of self-similar traffic. We explicate out methodology for discerning and evaluating the impact of changes in transport protocols in the protocol stack under self-similar traffic conditions. We discuss issues arising in comparative performance evaluation under heavy-tailed workload. workload.

• Journal of the Ergonomics Society of Korea
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• v.30 no.5
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• pp.671-681
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• 2011

Objective: The purpose of this study is to compare the workload level at each lower limbs posture and suggest the ergonomic workstation guideline for working period by evaluating the imbalanced lower limbs postures from the physiological and psychophysical points of view. Background: Many workers like welders are working in various imbalanced lower limbs postures either due to the narrow working conditions or other environmental conditions. Method: Ten male subjects participated in this experiment. Subjects were asked to maintain 3 different lower limbs postures(standing, squatting and bending) with 3 different working conditions(balanced floor with no scaffold, imbalanced floor with 10cm height of scaffold, and imbalanced floor with 20cm height of scaffold). EMG data for the 4 muscle groups(Retus Femoris, Vastus Lateralis, Tibialis Anterior, Gastrocnemius) from each lower limbs posture were collected for 20 seconds every 2 minutes during the 8 minutes sustaining task. Subjects were also asked to report their discomfort ratings of body parts such as waist, upper legs, lower legs, and ankle. Results: The ANOVA results showed that the EMG root mean square(RMS) values and the discomfort ratings(CR-10 Rating Scale) were significantly affected by lower limbs postures and working time(p<0.05). The correlation was analyzed between the EMG data and the discomfort ratings. Also, prediction models for the discomfort rating for each posture were developed using physical condition, working time, and scaffold height. Conclusion: We strongly recommend that one should not work more than 6 minutes in a standing or squatting postures and should not work more than 4 minutes in a bending posture. Application: The results of this study could be used to design and assess working environments and methods. Furthermore, these results could be used to suggest ergonomic guidelines for the lower limbs postures such as squatting and bending in the working fields in order to prevent fatigue and pain in the lower limbs body.

• International Journal of Computer Science & Network Security
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• v.21 no.12spc
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• pp.696-702
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• 2021

Informatization of early childhood education in the EU occurs in the context of the use of ICT as a means of sharing experiences, practices in the education and training of preschool children, communication, both at the national level and locally - within educational institutions, as a means of document management, search, data processing and information for the management of early childhood educational institutions, and planning activities for these institutions. This article aims to identify the features of the informatization of early childhood education in EU countries. Results. The countries of the EU have different levels of workload on the staff of early childhood education institutions, which is caused by different numbers of preschoolers and workforce. The greatest load on the staff in France due to a large number of preschoolers, which, despite the reduction, remained the highest among all the countries. By comparison, Poland's significant workload is mitigated by the size of its workforce. With almost equal numbers of staff in Poland and Germany, the countries differ significantly in the number of preschoolers. The countries also have different funding mechanisms for early childhood education, which determines the potential for digitalization. In France, total spending on early childhood education has grown the least (by 11 % between 2012 and 2018), in Poland by 51 %, in the Czech Republic by 44 %, and in Germany by 49%. In France, 100 % is funded by the government, in Poland 78 % is funded by the government, in the Czech Republic and Germany 87 % and 85 % respectively is funded by the government. The results of the survey of teachers' training in the use of ICTs and the level of specialists' readiness to use them in their studies indicate a mismatch between education and the practice of using technology. At the same time, given the high level of professional training of teachers in the use of technology in education, a low level of practice of ICT use in teaching preschool children was revealed. Teachers require professional development of ICT skills.

• Journal of the Korean Dietetic Association
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• v.30 no.2
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• pp.140-151
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• 2024

This study evaluated the effectiveness of an obesity program developed to solve 'obesity', which was selected as the top priority for urgent improvement among the dietary problems of elementary school students in Busan. The program aimed to practice four health rules every day (sleep early, eat two vegetables with each meal, reduce sugary snacks, and exercise for 30 minutes every day). The participants were trained to practice the four rules online in real time every day for three weeks, and their performance in nutrition education tasks was monitored using Padlet. The anthropometric measurements showed no change in the overall average weight before and after participating in the program, but all students grew in height (z=-6.978, P<0.001), and the number of obese students decreased significantly (z=-3.317, P<0.001). This obesity program was effective in improving height growth and obesity in elementary school students. In terms of dietary changes, after participating in the program, the frequency of vegetable consumption increased significantly (z=-4.849, P<0.001), the frequency of sweet snack consumption decreased significantly (z=-4.298, P<0.001), and the bedtime improved (z=-1.000). Therefore, the non-face-to-face, self-directed obesity program developed in this study is expected to reduce the workload of nutrition teachers carrying a heavy workload such as meal service and nutrition classes, and can be used as an efficient nutrition counseling program.

• Korean Journal of Community Nutrition
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• v.17 no.5
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• pp.652-663
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• 2012

The purpose of this study was to assess the physical activity level of Korean farmers to establish estimated energy requirements during the off-season. Subjects were 90 healthy males (n = 25) and females (n = 65). Body weight, height and body fat and muscles of subjects were measured. The prevalence of obesity among farmers was 56.7% according to the BMI. The farmers spent about 18 hours 7 minutes (75.5%) in sleeping and resting. The farmers spent about 19 hours 56 minutes (83.1%) out of 24 hours (one day) in "sedentary activities" and spent about 3 hours 56 minutes (16.4%) in "light activities". Physical activity level (PAL, activity coefficient) of female farmers was 1.42 which was not significantly higher than that (1.37) of male farmers. Estimated energy requirements (EER) for farmers who were different in age groups and gender were calculated. For example, the EERs for male and female farmers were 2190 kcal/day and 1712 kcal/day, respectively. The daily energy intakes of male and female farmers were 1803 kcal/day and 1610 kcal/day, respectively. The EER of male farmers was 2190 kcal/day which was significantly higher than that (1803 kcal/day) of the recommended daily energy intake of male farmers. The results of this study suggest that estimated EER of farmers should be modified according to seasonal workload and energy balance of farmers should be evaluated to prevent obesity.

• Journal of the Ergonomics Society of Korea
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• v.19 no.2
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• pp.15-31
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• 2000

The aim was to evaluate the prevailing ergonomic and psychosocial conditions regarding low back injury in an automobile assembly system. This study consisted of two parts. In the first part of the study, analytic biomechanical model and NIOSH guidelines were applied to evaluate risk levels of low back injury for automobile assembly jobs. Total of 246 workers were analysed. There were 20 jobs having greater back compressive forces than 300kg at L5/S1. Also, there were 44 jobs over Action Limit with respect to 1981 NIOSH guidelines. This might in part be explained by the ergonomic conditions of the company analysed generally being good, with a relatively low duration of 'combined' extreme work posture. The relationship between psychosocial factors and low back injury was examined in the second part of the study. It has recently been recognized that overall reaction to working conditions was influenced by a range of factors, some of which were physical and some psychosocial. The psychosocial environment surrounding the work place may contribute to the perception of risk and eventual ill-health. A battery of questionnaires concerning the psychosocial stress based on PWI(Psychosocial Well-being Index) and musculoskeletal pain symptoms at low back was completed by 246 workers at the same plant. Results showed that 207 out 246 workers experienced the symptoms and 27 workers were diagnosed as patients. Two groups(low stressed, high stressed) based on PWI score had no significant relationships with both symptoms and results of diagnosis. However, sensitivities for symptoms and diagnosis by PWI were 91.3% and 92.6% respectively. Finally, relationships between physical work load and psychosocial stress were analysed. Specifically, some postural factors {vertical deviation angle of forearm, horizontal deviation angle of upperarm, vertical deviation angle of thigh, etc) were highly correlated with psychosocial stress. The results illustrated that PWI scores were associated with some physical workloads. However, psychosocial stress levels couldn't be well related with the pain symptom as well as the actual incidence of low back injury since pain or discomfort regarding low back injury were more complex than that of other musculoskeletal disorders.

• Journal of Biosystems Engineering
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• v.35 no.5
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• pp.357-365
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• 2010

Workers in the agricultural industry have been exposed to many work-related musculoskeletal disorders. So, our objectives in this study were to measure and analyze worker's physiological bio-information to reduce musculoskeletal disorders in relation to agricultural works. We investigated worker's bio-information of physiological signals during the repeated lifting work such as body temperature, heart rate, blood pressure, physical activity, and heart rate variability. Moreover, we analyzed the workloads of lumbar spine during the repeated lifting work using the 3-axis acceleration and angular velocity sensors. The changes of body temperature was not significant, but the mean heart rate increased from 90/min to 116/min significantly during 30 min of repeated lifting work (p<0.05). The average worker's physical activity(energy consumption rate) was 206 kcal/70kg/h during the repeated lifting work. The workers' acute stress index was more than 80, which indicated a stressful work. Also, the maximum shear force on the disk (L5/S1) of a worker's lumbar spine in static state was 500N, and the maximum inertia moment was 139 $N{\cdot}m$ in dynamic state.

• Journal of the Ergonomics Society of Korea
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• v.29 no.4
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• pp.495-503
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• 2010

The packing and sorting processes of grape are required repetitive movements to need considerable physical load for a long time. And thereby, there is strong possibility to cause musculoskeletal disorders. In this study, ergonomically designed convenience equipments of worktable and handcart are introduced for improvement of the working movements and less physical load to increase the work efficiency. For objective analysis of the movements and the workload between the ones before and after the improvement, we measured heart rate, OWAS, RULA, REBA, LMM, moving Line and work time. Also, we used a checklist of physical fatigue regions to confirm the subjective evaluation of physical load of workers. As the result of study, it showed lower heart rate, value of Working Postures (OWAS, RULA, REBA) and LMM in the work after introduction of those convenient equipments than the work of before the introduction. The work time and moving Line were shortened and the number of grape boxes packed within the same work time was increased, too. Also the overall load as the subjective evaluation was reduced.