• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.3
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• pp.239-247
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• 2008

Low back disorders (LBDs) have been the most common musculoskeletal problem in Korean workplaces. It affects many workers, and is associated with high costs to many companies as well as the individual, which can negatively influence even the quality of life of workers. The _evaluation of low back disorder risk associated with manual materials handling tasks can be performed using variety of ergonomic assessment tools such as National Institute for Occupational Safety and Health (NIOSH) Revised Lifting Equation (NLE), the Washington Administrative Code 296-62-0517 (WAC), the Snook Tables etc. But most of these tools provide limited information for choosing the most appropriate assessment method for a particular job and in finding out advantage and disadvantage of the methods, and few have been assessed for their predictive ability. The focus of this study was to _evaluate spinal loads in real time with lifting and pulling heavy cow leathers in variety of postures. Data for estimating mean trunk motions were collected as employees did their work at the job site, using the Lumbar Motion Monitor. Eight employees (2 males, 6 females) were selected in this study, in which the load weight and the vertical start and destination heights of the activity remained constant throughout the task. Variance components (three dimensional spaces) of mean trunk kinematic measures were estimated in a hierarchical design. They were used to compute velocity and acceleration of multiple employees performing the same task and to repetitive movements within a task. Therefore, a results of this study could be used as a quantitative, objective measure to design the workplace so that the risk of occupationally related low back disorder should be minimized.

• Journal of the Korean Society of Costume
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• v.67 no.3
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• pp.81-98
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• 2017

The purpose of this study is to provide basic information for the development of pants patterns with a high level of fit and comfort through calculating surface variations of lower body parts by movement, grouping them into factors, and analyzing how their surface variations link to one another. The achieved results will help determine essential elements for constructing pants patterns, such as key measurements of lower body parts, the amount of ease values and selection of fabrics, which should be taken into consideration for allowing better movement in clothing. The study required lower body 3D scanning of women for analysis, and 13 women between the ages of 20-24 participated in the scanning, which was done by using Artec Eva 3D scanner. Their scanned data were digitalized and converted to measure the values of their lower body surface length and girth in pre-determined positions such as walking, stair climbing and sitting on a chair. These measurements have been statistically analyzed through SPSS 21.0 to obtain the average amounts and rates of extension for each of the measurement item. Some of the highlighted study results are as follows: The surface length and girth measurements were grouped into 4 factors based on their average extension rates. The results from correlation analysis between measurement items within each factor demonstrated that common items linked to all the changes in the values of other items in the three movements. But in most cases, items were not always correlated with each other for different movements. The results also showed that there were correlations between girth measurements, length measurements, and girth and length measurements. Therefore, key measurements for daily pants should be determined within reasonable estimations between relevant measurement items, while the measurements for work pants, which often withstand certain postures or repetitive movements, may require measurement items that are appro priate for, and closely related to, certain movements or tasks.

• The Journal of Korean Physical Therapy
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• v.18 no.6
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• pp.67-75
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• 2006

Purpose: Many kinds of musculoskeletal disease and symptom are caused by the longtime computer works. However, trapezius muscle tonus has not been established in regarding to keyboard height during typing. Therefore, this study is to evaluate the relationship between trapezius muscle tonus and the height of keyboard while typing, controling for the postures of neck, Lumbar, cervical vertebra. Methods: The experimental height of keyboard was set at elbow height, 3cm higher, 6cm higher, 9cm higher, than elbow. We studied trapezius tonus with the mean value for 2 minutes by EMG in 15 males and 15 females worker of hospital in seoul, who did not have a history of muscle disease, neurological signs, nerve damage. Results: In this experimental, as the height of the keyboard went up, the trapezius tonus significantly increased with shoulder abduction of brachium. Second, right and left trapezius tonus appeared similar while typing. Third, the best height that release the trapezius tonus the was as high as elbow and 3cm higher than elbow. Conclusion: With these above results, we suggest that the appropriate height of keyboard during typing to release the trapezius tonus most is the height of the elbow and 3cm higher than elbow. The study has important implications for focusing on the height of VDT worktable and complaining of a pain by oneself which are useful to establish a method of prevention of musculoskeletal disorder in work in the future.

• Journal of Animal Environmental Science
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• v.8 no.3
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• pp.171-176
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• 2002

Physical parameters of milk cow were measured to design and build RMS(Robotic Milking System) with a tape-measurer and body parameter measurer. The parameters are very important variables to design an RMS. For the working zone space of an RMS manipulator and the movement blunting of milk cow, an interval frame was installed on the stall bottom, and then cow's behavioral reactions were tested. The results from this study is summarized as follow. 1. On the general physical condition measurement, the maximum, minimum and average body length of cow which is related to the space that the manipulator could work into the RMS were 175cm, 144cm, and 163cm respectively. It appeared that the average distance between bottom and chest was 60cm. 2. The average length between fore teats, fore and hind teats and hind teats were 178mm, 150mm and 95mm respectively. It appeared that the average length between bottom and teat attachments was 544mm, and the average length between fore teats and tail-end was 331mm. 3. Although a cow kept a some extent length between hind legs for milking, it looked a stable pose. However, the cow kept a some extent distance between front legs for milking, it looked a unstable pose. Based on results of this test, an interval frame of stall bottom should be installed around the position which was located at its hind legs.

• Journal of the Korean Society of Safety
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• v.24 no.2
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• pp.83-88
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• 2009

The objective of this paper was to evaluate the effectiveness of horizontal, vertical, asymmetric and coupling multipliers for manual material handling. Lifting tasks with 5 different horizontal distances ($30{\sim}70cm$) for 6 vertical distances(ankle, knee, waist, elbow, shoulder and head height) were experimented. The muscle activity and muscle exertion level during asymmetric load handling(without trunk flexion) was experimented. Lifting tasks with and without handle tote box for three postures(straight, bending, right angle posture) were experimented. The degrading tendency did not appeared almost in $60{\sim}70cm$ interval's horizontal distance. As a result of ANOVA, MVC paid attention to horizontal and vertical distance but cross effect was insignificant(p<0.01). The change of the MVC according to the horizontal, vertical distance appeared similar from of RWL. The results of normalized MVC measurement were decreased about 16%, 24%, 34% respectively as the asymmetry angle was $30^{\circ}$, $60^{\circ}$, $90^{\circ}$. RMS EMG values of right erector spinae muscles were decreased as the work posture went to $90^{\circ}$ and those of left erector spinae muscles were increased until the asymmetry angle was $40^{\circ}$ but decreased continually over $40^{\circ}$. 7 subjects, activities of left and right latissimus dorsi muscles were maintained constantly, while for remainer, those were irregular. MVC reduced maximum 23% by type of handle. MVC was highest in straight posture, but was lowest in right angle posture. As a result of ANOVA, MVC paid attention to posture, coupling(p<0.01). To all handle types, biceps brachii activity was increased in right angle posture, but reduced in straight posture. Based on the results of this study, it is suggested that the NIOSH guideline should not be directly applied to Korean without reasonable reexamination. In addition, we need to afterward study through an age classification.

• Journal of Biosystems Engineering
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• v.40 no.1
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• pp.28-34
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• 2015

Purpose: This study aimed to install an RTK-GPS (Real Time Kinematic-Global Positioning System) and IMU (Inertial Measurement Unit) on a tractor used in a farm to measure positions, pasture topography, posture angles, and vibration accelerations, translate the information into maps using the GIS, analyze the characteristics of grass harvesting work, and establish new technologies and construction standards for pasture infrastructure improvement based on the analyzed data. Method: Tractor's roll, pitch, and yaw angles and vibration accelerations along the three axes during grass harvesting were measured and a GIS map prepared from the data. A VRS/RTK-GPS (MS750, Trimble, USA) tractor position measuring system and an IMU (JCS-7401A, JAE, JAPAN) tractor vibration acceleration measuring systems were mounted on top of a tractor and below the operator's seat to obtain acceleration in the direction of progression, transverse acceleration, and vertical acceleration at 10Hz. In addition, information on regions with bad workability was obtained from an operator performing grass harvesting and compared with information on changes in tractor posture angles and vibration acceleration. Results: Roll and pitch angles based on the y-axis, the direction of forward movements of tractor coordinate systems, changed by at least $9-13^{\circ}$ and $8-11^{\circ}$ respectively, leading to changes in working postures in the central and northern parts of the pasture that were designated as regions with bad workability during grass harvesting. These changes were larger than those in other regions. The synthesized vectors of the vibration accelerations along the y-axis, the x-axis (transverse direction), and the z-axis (vertical direction) were higher in the central and northwestern parts of the pasture at 3.0-4.5 m/s2 compared with other regions. Conclusions: The GIS map developed using information on posture angles and vibration accelerations by position in the pasture is considered sufficiently utilizable as data for selection of construction locations for pasture infrastructure improvement.

• Fashion & Textile Research Journal
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• v.6 no.6
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• pp.707-714
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• 2004

This study was carried out to research the actual condition of narrator models' wearing uniform, targeting on the narrator models who are being currently active and are from 19-year-old to 30-year-old. A poll was performed through visiting internet circles and spots, and the characteristic of objects, the form of uniform, attitude on uniform, dissatisfaction index on wearing uniform and preference index on wearing uniform were researched. It was carried out from August 18, 2003 to August 31, 2003. In order to perform this study, 161 questionnaires were used in all, and frequency analysis was implemented using SPSS 10.0. The objects of study were composed of female. Those who are from 21-year-old to 25-year-old accounted for 74.5%, and those who have career from 2 years to 3 years accounted for 75.5%. In respect to attitude on wearing uniform, affirmative answers, affirmative answers, such as a sense of belonging, a pride in activity and increase of efficiency, accounted for 68.8%. On the other hand, in respect to a harmonization between uniform and work, just the 39.8-percent showed affirmative reaction. Concerning the functionality of uniform, such as retaining warmth and ventilating, dissatisfaction index showed very high value; it is judged that it should be improved henceforth. Working postures were researched, following the order of standing posture and arm-using posture. In inconvenient actions, bending down and moving arms were orderly pointed out. With regard to the dissatisfaction of size, busts, the length of skirt and waist girth were orderly pointed out. Likewise, considering the parts of which room is required, bust, hip girth and waist girth were orderly pointed out. As to the points that should be bettered, design and functionality were orderly pointed out. In respect to materials of uniform, sweat-absorption material, light material and well-ventilated material were orderly suggested.

• Safety and Health at Work
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• v.9 no.2
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• pp.125-132
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• 2018

Background: According to the US Bureau of Labor Statistics, musculoskeletal disorders (MSDs) accounted for 32% of all nonfatal injury and illness cases in 2014 among full-time workers. Our objective was to review and summarize the evidence linking occupational exposures to vibration and awkward posture with MSDs of the shoulder and neck. Methods: A literature search was conducted using the terms musculoskeletal disorders, vibration, and awkward posture. All types of observational epidemiologic studies, with the exception of case reports, published during 1998-2015 were included. Databases searched were MEDLINE (Ovid), Embase (Ovid), Scopus, Ergonomic Abstracts, NIOSHTIC-2, and Health and Safety Science Abstracts. Results: Occupational exposures to whole-body or hand-arm vibration were significantly associated with or resulted in MSDs of the shoulder and neck. Awkward postures while working were also associated with MSDs in these locations. These findings were consistent across study designs, populations, and countries. Conclusion: Occupational exposure to vibration and awkward posture are associated with shoulder and neck MSDs. Longitudinal studies are required to elucidate the mechanisms responsible for these associations, and intervention studies are warranted.

• Journal of the Korea Safety Management & Science
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• v.16 no.4
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• pp.371-378
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• 2014

Manual materials handling tasks are the main risk factors for the work-related musculoskeletal disorders. Many assistant tools for manual materials handling are being used in various kind of industries. One of them is a 4-wheeled cart which is widely used in manufacturing factories, hospitals, etc. The major force required to control the 4-wheeled cart is pushing and pulling. There are two types of handles being used for the 4-wheeled cart : vertical type (two vertical handles), and horizontal type (one horizontal handle). This study tried to investigate the pushing forces and subjective discomforts (hand/writst, shoulder, low back, and overall) of the two handle types with different handle height and distance conditions. Twelve healthy male students (mean age = 23.4 years) participated in the experiment. The independent variables were handle angle (horizontal, vertical), handle height (low, medium, high), and handle distance (narrow, medium, wide). The full factorial design was used for the experiment and the maximum pushing forces were measured in 18 different conditions ($2{\times}3{\times}3$). Analysis of variance (ANOVA) procedure was conducted to test the effects of the independent variables on the pushing force and discomfort levels. Handle height and angle were found to be the critical design factors that affect the maximal pushing forces and subjective discomfort. In the middle height, subjects exerted higher pushing forces, and experience lower discomfort levels compared to the high, and low height. There was no statistical influence of the handle distance to the pushing forces and subjective discomfort levels. It was found out that the effects of the handle angle (horizontal and vertical) on both pushing force and subjective discomfort were statistically significant (p < 0.05). The vertical handle revealed higher pushing force and lower discomfort level than the horizontal handle. The reason for that was thought to be the different postures of the hand when grasping the handles. The horizontal handle induced pronaton of the hand and made hand posture more deviated from the neutral position.

• Journal of the Ergonomics Society of Korea
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• v.26 no.2
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• pp.35-44
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• 2007

Work-related musculoskeletal disorders (WMSDs) are a major problem in industries in which manual materials handling is performed by workers. To prevent these WMSDs, it is necessary to understand the muscular strength capability and use this knowledge to design job and selection and assignment of workers. 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. However, a few researches have been done for one-hand lifting activity of manual materials handling tasks. The objective of this study is to compare one-hand and two-hands lifting strength in terms of static and dynamic strength of the lifting activity for the ranging from the height of knuckle to elbow. It is shown in this study that the isometric lifting strength of one-hand is ranging from 54.7 to 63.3% of the one of two-hands. However, it is found that there is no significant difference between a person's isometric lifting strength for left-hand and right-hand. It is also shown that there is no significant difference between the peak force under the dynamic sub-maximal loading with one-hand and two-hands lifting activity. Similar results were obtained for the peak acceleration and peak velocity under the dynamic sub-maximal loading with one-hand and two-hands lifting activity. Isometric lifting strength at the height of knuckle was ranging from 2 to 3 times of the dynamic peak force during sub-maximal lifting. It is concluded that the dynamic peak forces under the sub-maximal loading are not highly correlated with the isometric lifting strength in similar postures.