• Journal of the Korean Society of Safety
• /
• v.24 no.2
• /
• pp.76-82
• /
• 2009

The NIOSH lifting equation has been used as a dominant tool in evaluating the hazard levels of lifting tasks. Although it provides two different ways for each simple and complex lifting task, the NIOSH simple lifting equation is almost used for not only simple tasks but also complex tasks. However, most of lifting tasks in industries are in the form of complex lifting. Therefore some errors occur inevitably in the evaluation of complex lifting tasks. Among complex lifting tasks, a multi-stacking task is the most popular in lifting tasks. To compensate the error in the evaluation of multi-stacking tasks by using the NIOSH simple lifting equation, a set of calculations for finding LIs(Lifting Indices) was performed for the systematically varying multi-stacking tasks. Then a regression model which finds the equivalent height in simple lifting task for multi-stacking task was established. By using this model, multi-stacking tasks can be evaluated with less error. To validate this model, some real multi-stacking tasks were evaluated as examples.

• Journal of the Ergonomics Society of Korea
• /
• v.30 no.5
• /
• pp.597-603
• /
• 2011

Objective: The objective of this study was to compare one-hand and two-hands lifting activity in terms of biomechanical stress for the range of lifting heights from 10cm above floor level to knuckle height. Background: Even though two-hands lifting activity of manual materials handling tasks are prevalent at the industrial site, many manual materials handling tasks which require the worker to perform one-hand lifting are also very common at the industrial site and forestry and farming. Method: Eight male subjects were asked to perform lifting tasks using both a one-handed as well as a two-handed lifting technique. Trunk muscle electromyographic activity was recorded while the subjects performed the lifting tasks. This information was used as input to an EMG-assisted free-dynamic biomechanical model that predicted spinal loading in three dimensions. Results: It was shown that for the left-hand lifting tasks, the values of moment, lateral shear force, A-P shear force, and compressive force were increased by the average 43%, as the workload was increased twice from 7.5kg to 15.0kg. For the right-hand lifting task, these were increased by the average 34%. For the two-hands lifting tasks, these were increased by the average 25%. The lateral shear forces at L5/S1 of one-hand lifting tasks, notwithstanding the half of the workload of two-hands lifting tasks, were very high in the 300~317% of the one of two-hands lifting tasks. The moments at L5/S1 of one-hand lifting tasks were 126~166% of the one of two-hands lifting tasks. Conclusion: It is concluded that the effect of workload for one-hand lifting is greater than two-hands lifting. It can also be concluded that asymmetrical effect of one-hand lifting is much greater than workload effect. Application: The results of this study can be used to provide guidelines of recommended safe weights for tasks involved in one-hand lifting activity.

• Kyungpook Mathematical Journal
• /
• v.45 no.3
• /
• pp.445-453
• /
• 2005

We say that a module M is weak lifting if M is supplemented and every supplement submodule of M is a direct summand. The module M is called lifting, if it is weak lifting and amply supplemented. This paper investigates the structure of weak lifting modules and lifting modules having small radical over commutative noetherian rings.

• Journal of the Ergonomics Society of Korea
• /
• v.21 no.1
• /
• pp.27-32
• /
• 2002

The objective of this study was to investigate the effects of fatigue, caused by frequent manual lifting. on lifting velocity and lifting acceleration. Ten male volunteers performed lifting at a rate of 4 times per minute, continuously, for two hours using the free-style posture A box($30cm{\times}30cm{\times}20$) with a fixed weight (15.9 Kg) was used as the load for lifting, Heart rate, oxygen consumption, and EMG were also measured to estimate the level of fatigue, The posture as well as acceleration was recorded. The results showed that the lifting acceleration at the end of two hour increased significantly (20%, p<0.001) compared to the acceleration after fifteen minutes of lifting. It was also found that subjects changed their lifting postures as the result of fatigue. All subjects also indicated pain in their upper legs and the lower back at the conclusion of the experiment.

• Journal of Industrial Convergence
• /
• v.1 no.2
• /
• pp.17-31
• /
• 2003

Many risk factors with the onset of Low Back Pain(LBP) have been identified, however, lifting out of Manual Material Handling(MMH) was the most important factor to the LBP. Injuries due to lifting took account for 34.0%(227,291) out of the total overexertion in MMH(668,084). The weight, vertical location, twist angle, lifting frequency, and lifting posture were reviewed in this study. Technical information for using the revised lifting equation to evaluate a variety of two - handled manual material handling tasks was suggested. To measure worker's fatigue in lifting task, Lifting Index Simulator(LIS) was create under the revised NIOSH(National Institute for Occupational Safety and Health) lifting equation. For the implementation of the LIS, data was collected in A company manufactures various paints in Si-Wha industrial complex, Kyunggi-Do. The results of the Lifting Index(LI) were analyzed by MANOVA to find the relation with lifting variables collected. It was found that horizontal distance, vertical distance, travelling distance and frequency were significant at the 0.01 level and weight was significant at the 0.05 level. The purpose of this paper is to reduce the chronical low back pain for the manual material handlers.

• Proceedings of the ESK Conference
• /
• 1992.10a
• /
• pp.18-21
• /
• 1992

The objective of this study was to investigate the effects of fatigue, caused by frequent manual lifting, on lifting velocity and lifting acceleration. Ten male volunteers performed lifting at a rate of 4 times per minute, continuously, for two hours using the free-style posture. A box $(30cm{\times}30cm{\times}20cm)$ with a fixed weight (15.9kg) was used as the load for lifting. Heart rate, oxygen consumption, and EMG were also measured to estimate the level of fatigue. The posture as well as acceleration was recorded. The results show that the lifting acceleration at the end of two hour increased significantly (20%, p<0.001) compared to the accleration after fifteen minutes of lifting. It was also found that subjects changed their lifting postures as the result of fatigue. All subjects also indicated pain in their upper legs and the lower back at the conclusion of the experiment.

• Journal of computational fluids engineering
• /
• v.3 no.2
• /
• pp.52-64
• /
• 1998

Numerical simulations on the flowfield of lifting chamber for Wing-In-Ground vehicle were performed using Fluent/UNS 4.2 software. The trend of lifting force in lifting chamber and parametric study of geometric and fluid variables were primarily investigated. Selected parameters for investigation are inlet velocity, height between chamber and water level, depth of the skirt, location of inlet, variaton of height at bow and stern. Also, air capturing capabilities from downstream of the propeller were evaluated at the air inlet. The lifting force was increased linearly with the increased of inlet velocity and nonlinearly with the decrease of height force was increased with increased depth. It turned out to have very minor effect on lifting force to change the location of air inlet for lifting chamber, installed on top surface. Tilting the vehicle when it was lifted, the lifting forces, generated in each case, showed no appreciable changes.

• Journal of the Korean Mathematical Society
• /
• v.57 no.3
• /
• pp.793-807
• /
• 2020

Stable range of rings is a unifying concept for problems related to the substitution and cancellation of modules. The newly appeared element-wise setting for the simplest case of stable range one is tempting to study the lifting property modulo ideals. We study the lifting of elements having (idempotent) stable range one from a quotient of a ring R modulo a two-sided ideal I by providing several examples and investigating the relations with other lifting properties, including lifting idempotents, lifting units, and lifting of von Neumann regular elements. In the case where the ring R is a left or a right duo ring, we show that stable range one elements lift modulo every two-sided ideal if and only if R is a ring with stable range one. Under a mild assumption, we further prove that the lifting of elements having idempotent stable range one implies the lifting of von Neumann regular elements.

• Kyungpook Mathematical Journal
• /
• v.60 no.4
• /
• pp.673-682
• /
• 2020

For the recently defined notion of strongly lifting modules, it has been shown that a direct sum is not, in general, strongly lifting. In this paper we investigate the question: When are the direct sums of strongly lifting modules, also strongly lifting? We introduce the notion of a relatively strongly projective module and use it to show if M = M1 ⊕ M2 is amply supplemented, then M is strongly lifting if and only if M1 and M2 are relatively strongly projective and strongly lifting. Also, we consider when an arbitrary direct sum of hollow (resp. local) modules is strongly lifting.

• Ocean Systems Engineering
• /
• v.5 no.3
• /
• pp.181-198
• /
• 2015

An OSV (Offshore Support Vessel) is being used to install a structure which is laid on its deck or an adjacent transport barge by lifting off the structure with its own crane, lifting in the air, crossing splash zone, deeply submerging, and lastly landing it. There are some major considerations during these operations. Especially, when lifting off the structure, if operating conditions such as ocean environmental loads and lifting off velocity are not suitable, the collision can be occurred due to the relative motion between the structure and the OSV or the transport barge. To solve this problem, this study performs the physics-based simulation of the lifting off step while the OSV installs the structure. The simulation includes the calculation of dynamic responses of the OSV and the structure, including the collision detection between the transport barge and the structure. To check the applicability of the physics-based simulation, it is applied to a problem of the lifting off step by varying the ocean environmental loads and the lifting off velocity. As a result, it is confirmed that the operability of the lifting off step are affected by the conditions.