• Journal of the Ergonomics Society of Korea
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• v.34 no.3
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• pp.279-291
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• 2015

Objective: The purpose of the study is to evaluate appropriate weight for aged farmers in manually handling livestock feed in bags using ergonomic methods. Background: In the livestock industry in South Korea, despite the trend of aging of labor manpower, heavy items are still manually handled in many farms. In particular, among stockbreeding works, the handling of feed in bags weighing 25~30kg is reported as a cause of frequent injuries and musculoskeletal system diseases. However, studies on the standard for recommended weight allowed considering the physical characteristics of aged farmers older than 60 years with greatly decreased physical strength and muscle strength are insufficient. Method: To evaluate appropriate weight for handling of heavy livestock feed in bags, physical techniques for measuring recognized levels of physical work loads, the NLE (NIOSH lifting equation) a method that is an observation type technique, and an ergonomic modeling technique to predict compressive force imposed on L5/S1 were used. Subjects who participated in the experiment were organized into two groups of males/females with mean age exceeding 60 years, and lifting tasks were evaluated for nine weight levels. Results: Based on the results of psychophysical measurement, females showed a tendency of more drastic increases compared to males when weight was over 19kg. The results of estimation of regression models for the weight, 18.0 kg ($r^2=0.97$) and 15.3kg ($r^2=0.97$) were evaluated as stable load for males and females, respectively. In addition, both the observation type evaluation and ergonomic model evaluation showed stable loads in a range of 15~18kg. Conclusion: Given the results of the study, the weight of the feed in bags currently distributed to farms can become a cause of not only overexertion but also farm work related disasters such as musculoskeletal disorders and safety accidents. Providing livestock feed in bags weighing not more than 19kg for aged farmers is judged desirable, and managerial improvement for this matter is considered necessary. Application: The results of the present study can be utilized as useful data for institutional improvement of the weight of livestock feed in bags.

• Health Policy and Management
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• v.32 no.4
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• pp.368-379
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• 2022

Background: This study aimed to establish a strategy to improve the poor working environment and working conditions among long-term healthcare workers in Korea. Methods: A total of 600 questionnaires with which long-term health care workers participated in the targeted base areas of each city and province nationwide were distributed directly and 525 responses were collected and 506 responses were analyzed. Surveys, on-site field visits, and in-depth interviews were also conducted to understand the working environment as well as conditions and establish a strategy for improving the working environment among long-term healthcare workers to understand the demands of working conditions and working conditions. Results: Korean long-term care workers firstly and mostly enumerated their risk factors for ill-health when lifting or moving elderly recipients directly by hand (69.9%), followed by increased physical workload with old beds, tools, and facilities (42.3%) in the workplaces, shortage of manpower (32%), and source of infection (30%). To improve the working environment as well as conditions, Korean long-term care workers considered improving low-wage structures, ergonomic improvements to solve excessive physical loads, and increasing various bonus payments as well as implementing the salary system, positive social awareness, and increasing resting time. Of 506 responses, 92.3% replied that the long-term care insurance system for the elderly should be developed to expand publicization at the national level. Conclusion: This study proposes to improve the low-wage structure of Korean long-term care workers, automation and improvement of facilities, equipment, and tools to eliminate excessive physical loads (beneficiary elderly lifting), and reduction of night labor.

• Research in Community and Public Health Nursing
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• v.9 no.1
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• pp.213-222
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• 1998

The prevalence rate of low back pain in nurses is higher than that of other jobs, because there are many more risk factors(for example, standing postures, lifting and carrying heavy loads, transfering patients, changing a patient's position etc.). This investigation is to provide basic data for prevention of low back pain by analyzing the prevalence rate and related factors of low back pain in nurses(esp. operating room staff) in general hospitals. A self-reported questionaire survey was carried out on three hundred and five nurses of three general hospitals in Seoul from June, 1996 to August, 1996. Subjects of the survey were divided into a low back pain group(LBP) and a cotrol group to investigate the association between low back pain and the general characteristics and work related factors of each group. The results were as follows: 1. In the subjects of the survey, the prevalence rate of low back pain was 60.0% for the last year. 2. 73.6% of operating room(OR) staff complained of low back pain. 3. Standing for a long time and working in twisting postures were associated with low back pain, and so were the shift, the type of work, and the frequency of transfering patients. 4. The weight loads which nurses frequently carried were, under 5kg, 5-10kg, 15-20kg, 15-20kg, over 20kg, and all, except for 10-15kg, were associated with LBP. 5. 76.9% of the LBP experienced low back pain within 3 years after starting nursing jobs. 6. Concerning the degrees of low back pain: 75.8% was limited to waist; 18.8% reached the knees; 4.2% reached ankles. In conclusion, the prevalence rate of low back pain in general hospital nurses was associated with the works in operating room and other work related factors, therefore it is necessary to develop on educational program for the prevention of low back pain as well as and to improve working environments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6A
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• pp.389-398
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• 2012

In this study, structural strain responses of the jacket-type Uldolmok tidal current power plant structure under severe tidal environments were measured and analyzed using long-term measurement system during construction and also operation. It was observed that there were significant changes in strain responses at the steps of jacket lifting, block loading, pile ejection and insertion. Strains due to dead loads and tidal loads were analyzed before and after removal of a jacket leg, and it was also found that the strains due to dead load were much significantly changed after jacket leg removal. From the measurement data during operation, it was found that strain responses were fluctuated with M2 and M4 tidal periods and also relatively short period of about 10 min due to the peculiar tidal characteristics in the Uldolmok strait. Finally, the neural network-based non-parametric estimation models were investigated to build up the signal-based structural damage monitoring system.

• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.235-241
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• 2017

Purpose: It is to develop an agricultural three-directional dumping vehicle that can help farmers reduce intensive labor when carrying heavy loads and for easy dumping. In addition, a novel mechanism was applied for controlling the direction of the tilting cargo box by using a single hydraulic cylinder and simple apparatus. The overturning safety was analyzed to provide safe-use ground slope region of the vehicle to be used at upland fields and orchards. Methods: The developed three-directional dumping vehicle was constructed using a cargo box, vehicle frame, driving components, lifting components, and controller. The novel mechanism of controlling the dumping direction involves the operation of two latching bars, which selectively release or collapse the connecting edge between the vehicle frame and cargo box. A multibody dynamics analysis software (RecurDynV8R5) was used to determine the safe-use ground slope area when tilting the cargo box at slopes. A computer analysis was conducted by increasing the ground slope while rotating the vehicle when the cargo box comprised loads of 300 and 500 kg and stacking heights of 40 and 80 cm, respectively. Results: The three-directional dumping vehicle was successfully manufactured, and the cargo box was tilted at $37^{\circ}$ and $35^{\circ}$ for dumping forward and sideways. The latching bars were manually and selectively collapsed with the vehicle frame to control the dumping direction. When forward dumping, the safe-use ground slope was over $20^{\circ}$ in all vehicle directions and loaded conditions. Conclusions: A three-directional dumping vehicle was developed to reduce labor-intensive work in the farming environment. The user can easily control the dumping direction by using the control panel. The vehicle was safe to be used in most of the Korean upland fields and orchards (area over 96%) for the forward dumping.

• Advances in aircraft and spacecraft science
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• v.1 no.3
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• pp.291-310
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• 2014

An advanced model for the linear flutter analysis is introduced in this paper. Higher-order beam structural models are developed by using the Carrera Unified Formulation, which allows for the straightforward implementation of arbitrarily rich displacement fields without the need of a-priori kinematic assumptions. The strong form of the principle of virtual displacements is used to obtain the equations of motion and the natural boundary conditions for beams in free vibration. An exact dynamic stiffness matrix is then developed by relating the amplitudes of harmonically varying loads to those of the responses. The resulting dynamic stiffness matrix is used with particular reference to the Wittrick-Williams algorithm to carry out free vibration analyses. According to the doublet lattice method, the natural mode shapes are subsequently used as generalized motions for the generation of the unsteady aerodynamic generalized forces. Finally, the g-method is used to conduct flutter analyses of both isotropic and laminated composite lifting surfaces. The obtained results perfectly match those from 1D and 2D finite elements and those from experimental analyses. It can be stated that refined beam models are compulsory to deal with the flutter analysis of wing models whereas classical and lower-order models (up to the second-order) are not able to detect those flutter conditions that are characterized by bending-torsion couplings.

• Journal of Power System Engineering
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• v.19 no.5
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• pp.17-24
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• 2015

In this paper, the development of an air cushion transporter has been studied. To do this, theoretical analysis is introduced to design the equipment and computational fluid dynamics is also conducted. Design of an air cushion transporter for heavy load carriage is completed and a prototype is manufactured. Through the analysis and experiment of the developed the prototype, it can be known that the developed transporter can levitate the load of about 1 ton at the applied pressure of 0.2 MPa and the maximum lifting height at this condition is 17mm.

• Korean Journal of Occupational Health Nursing
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• v.3
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• pp.21-30
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• 1993

For the purpose of disclosing the magnitude of low back pain problems of hospital nursing personnel and its possible causes, a questionaire survey was carried out on 418 nurses and nurse aides if a university hospital in Seoul. The results were as follows : 1. Of 418 nurse and nurse aides, 268 persons(64.1%) have experienced 1,145 spells of low back pain during 6-month period. 2. The pain and/or discomfort was mostly limited to the back, although 19% of the episodes accompanied radiating pain to the low extremities. 3. Of those with low back pain, 23 persons(8.6%) were medically diagnosed and 17 persons(6.3%)-underwent medical treatment. Those who sick leave amounted to 8 persons(3.0%). 4. The occurrence of low back pain showed significant association with assignment of duties(wards) and work shifts, while the association was not significant in terms of ranks, careers and overtimes. 5. The occurrence of low back pain was closely associated with lifting and carrying of loads, standing and twisting postures as well as the amount of work. 6. Among the nonoccupational factors, drinking showed statistically significant association with the occurrence of low back pain.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.6
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• pp.711-719
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• 2019

At present, wind power is the fastest growing technology in the world. The domestic market depends heavily on imports for wind tower lift. so it manage through the overseas maker. The lift manufacture, establishment and maintenance utility is increasing, localization development of one wind tower lift is necessary with domestic fundamental base technique. In this paper, we will study the components necessary for the development of onshore offshore wind tower elevators, which are currently dependent on total imports, in line with the high growth of the wind market and the enlargement of the wind power generators. First of all, endless winders and cabins, which are the core components of the offshore wind tower lift, were examined for the components that affect the structural safety. Structural analysis was performed on Sheave, which is responsible for most of the lift lifting loads, and Block Stop, a safety device that prevents the cabin from falling in an emergency. The structural suitability was evaluated by comparing with the safety factor. In addition, the on-board control panel combines the control panel of the elevator and the drive motor driving the endless winder for efficient control of the offshore wind tower lift. The addition of features improves ride comfort at departure.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.10
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• pp.3-10
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• 2018

Hybrid Prestressed Precast Concrete System (HPPC system) is a newly developed frame system that can improve the performance of precast concrete (PC) joints by post-tensioning. In particular, the details proposed in this study can reduce the lifting weight of the PC members and eliminate problems caused by cracks in the joints that occur under service loads. This study performed an evaluation on the negative moment performance of full-scaled HPPC girders. The test specimens were cast with or without slabs, with bonded or unbonded tendons, and had different post-tensioned lengths in tensile section. The test results showed that the specimens with slabs had significantly higher stiffness and strength than those without slabs. There were no differences in the flexural behavior between those with bonded or unbonded tendons, and between those with short or long post-tensioned lengths in the negative moment region.