• Journal of the Ergonomics Society of Korea
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• v.19 no.2
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• pp.75-86
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• 2000

In this study, the characteristics of transmitted vibration on HAS(hand-arm system) were identified to evaluate physical load due to the work surface orientation, tool weight and push force during powered drilling tasks. The characteristics of transmitted vibration on work surface orientation showed that the acceleration of transmitted vibration on horizontal work surface was higher than that on the vertical work surface. Regarding the characteristics of transmitted vibration on tool weight, the vibration acceleration level becomes lower as the tool weight becomes heavier. The amount of transmitted vibration on hand-arm system was decreased down to the tool weight of 2.4kg. However, as the tool weight becomes heavier than 2.8kg, the amount of transmitted vibration was increased and had peak value at 3.2kg of tool weight. Regarding the characteristics of transmitted vibration on push force, the vibration acceleration level goes higher, as the push force becomes larger. The characteristics of transmitted vibration on the axis of vibration showed that the direction of $Z_h$ had the highest acceleration compared to the direction of $X_h$, and $Y_h$. The direction of $X_h$, $Y_h$ and $Z_h$ had the highest acceleration of transmitted vibration on the hand, wrist and elbow, respectively. The results of this study showed that the condition which affect the lowest physical load to the subject on the powered drilling task would be working with the 2.4kg of tool weight on the vertical work surface.

• Journal of the Ergonomics Society of Korea
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• v.19 no.3
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• pp.93-107
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• 2000

The excessive exposure to powered hand tools can cause damage to nerves, impair blood circulation, and musculoskeletal damage. The symptoms associated with hand-arm vibration syndrome (HAVS) include numbness, tingling, pain and subsequent reduced dexterity of the hands. This study was performed to report the prevalence of the HAVS and evaluate its related factors among the workers using powered hand tools. Total 282 workers in 11 plants of Kyungki and Inchon areas were examined. A standard symptom questionnaire was developed and administered to collect information on personal characteristics, work history, operating conditions, tool characteristics, and subjective symptoms of HAVS. Mean values (standard deviations) of the age, the duration of powered hand tools used, and the daily hours using powered hand tools were 38.3(8.9) years, 79.3(62.2) months and 6.0(2.6) hours, respectively. 132 workers(46.8%) showed vibration-induced white finger symptoms according to the Taylor-Pelmear classification, and 30 workers(10.6%) were interfered with the work. The results of a multiple logistic regression analysis controlling for age and daily working hours showed that smoking, work duration, weight of tools, and continuous work over 2 hours were significantly associated with the symptom of HAVS.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.567-572
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• 2000

From the experimental study of W-EDM for alloyed steel, the characteristics such as Hand Drum Form and surface roughness have been observed and evaluated for various conditions. In square hole, the increase of IP as to made condition, the calculate high value of surface roughness. Also compare dimensionless square hole with circle hole' graph, In circle hole, if a value of surface roughness IP 6 in a side of circle it show a 0.4${\mu}{\textrm}{m}$ and in IP 8, 0.6${\mu}{\textrm}{m}$, in IP 10, 0.7${\mu}{\textrm}{m}$, in IP 12, 0.8${\mu}{\textrm}{m}$ higher than before. This figure show the surface roughness is higher than before, because a table move in either X-axis or Y-axis in square hole, on the contrary, in circle there table move in X-axis and Y-axis at the same time. hand drum form getting small when wire tension increase 1000gf to 1500gf, at the same working conditions. The smaller of off time, the maller of hand drum form in same condition and same wire tension. but if you compare square hole with circle hole' graph, hand drum form displayed in maintained term of working condision, on the contrary, in case of square hole variation of hand drum form is more increase than a grow of IP

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.2
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• pp.16-23
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• 2005

This study is intended to find out the reason of interference phenomenon of a machine tool when it operates for 5-axises working. The researcher made a Virtual Machine which has same figures of the 5 axises machine tool and Virtual Manufacturing System which has both Software factors - controller and NC code data to manipulate the movement characteristics of the machine - and Hardware factors - fixtures, workpiece, tools, holders and so on. With these virtual tools, this study is designed to find out the relation between the movement and the interference or collision, and also intended to verify the simulation and work-processing. In this study, the researcher found out, in case of the vertical 5 axises type, that it has more chances to have interference between the fixture, the workpiece and the main spindle including the tool holder due to the tilting kinetics of the main spindle. In case of the horizontal 5 axises type, on the other hand, the researcher found out that it has more possibility to have the interference between the main spindle and the rotary shaft.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.12 no.1
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• pp.121-130
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• 2005

Purpose: This study was done to determine the rate for handwashing by intensive care unit nurses according to the content of nursing tasks, to investigate the relationship between hand washing practice evaluated by nurses themselves and their actual practice observed, and finality to provide basic materials for strategy for hand washing education. Method: Data were collected by observing 27 nurses working in intensive care units of a hospital in Uijeongbu, Gyeonggi-do and by using observation and a structured self-assessment tool. Collected data were analyzed with SPSS and SAS. Results: The handwashing rate for the nurses was 4.3%. The handwashing rate was high in proportion to the risk of cross infection. In addition, the handwashing rate was highest in nurses working in the neurosurgery intensive care unit. The average score for self-assessment of handwashing was $49.42{\pm}3.78$ points and it was higher than their actual practice of handwashing. Conclusion: In order to improve handwashing by nurses, it is necessary to educate them on the importance of handwashing. In addition, there should be strategies for standardizing knowledge and attitudes to handwashing and inducing nurse:3 to practice hand washing in compliance with the policies and working conditions of the institution.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.57-58
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• 2012

Work to repeat the work using the tool since many occupational diseases such as musculoskeletal disorders, such as occupational low back pain is increasing. To solve this problem, previous(or existing) studies for improving the environment of construction workers are working, but the previous study was lack of approach that applied to condition of construction field. Thus, the objective of this paper will analysis the Correlation of musculoskeletal disease which is caused by Working Hand and Working Type for workers. The results of this Research through a die to improve the work environment of workers and prevention of musculoskeletal disorders in order to prepare is to provide basic data.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1865-1868
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• 2003

This paper provides a new method for hybrid machining, particularly suited to micro fabrication applications such as micro point, micro line, micro structure, micro partition and so on. Developed micro fabrication process by electrical discharge machining (EDM) and electrical discharge deposition (EDD) with metal powder (Ti, Fe) has been studied to build TiC or FeC structure. Titanium powder or iron powder is supplied from working fluid (kerosene or de-ionized water with powder) and adheres on a workpiece by the heat and electric power caused by the electrical discharge. The use of a tool electrode is expected to keep powder concentration high in the gap between a workpiece and a tool electrode and to accrete powder material on the workpiece. The deposition is tried under various electrical conditions (workpiece. tool electrode, working fluid, discharge current, voltage and powder etc.). On the other hand. using electrical discharge machining (EDM) with the same tool electrode, it can be used as a removal process (cutting) by electro erosion at the same time. Therefore. this new method can do a hybrid machining to build up and down a structure with the workpiece.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.6
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• pp.71-76
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• 2008

The focus of this paper is the designing a flexible three fingered hand system with 16 D.O.F for dynamic manipulation with an intelligent controller, and to build a useful database for dynamic manipulation based on the experimental results. The weight of the hand module is only 0.7 kg, but flexible motion and powerful grasping are possible. To achieve such a dynamic motion in a robotic hand, we have developed a flexible fingered hand with a control system incorporating image recognition system in which we deal with the problems of not only accuracy and range of motion but also the flexibility of hand. The fingers are arranged so as to grasp both circular and prismatic objects. In order to achieve the light mechanism, we reduced the number of joints and fingers as much as possible. We used three fingers, which is the minimum number to achieve a stable grasp.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.2
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• pp.103-114
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• 2023

Objectives: This study was conducted to evaluate hand-arm vibration (HAV) exposure levels due to the use of power hand tools and to evaluate the determinants in the automobile assembly process. Methods: The exposure level to HAV was evaluated for 30 work lines in five assembly processes (body, engine, chassis, door, and design) that use air-powered tools and battery-powered tools and operate in circulation for two hours. The 2-hr equivalent energy vibration acceleration, A (2), of the task was measured. The 8-hr equivalent energy vibration acceleration, A (8), was estimated in consideration of the number of tasks that can be performed per day by each process. In addition, a survey on the working environment was conducted with workers exposed to vibration. Results: The geometric mean of the HAV exposure level, A (2), for a total of 30 tasks was 2.51 m/s², and one case was 10.30 m/s², exceeding TLV (2hr). The HAV exposure level of A (8) was evaluated from 1.03 m/s² to 5.36 m/s². A (2) showed a statistically significant difference (P<0.01) for each process, and the chassis process (GM=3.90 m/s²) was the highest. The larger the tool size and the longer the tool length, the higher was the vibration acceleration when using a battery-powered tool than an air-powered tool (P<0.01). Battery-powered tool users showed higher dissatisfaction on all items than did air-powered tool users. Conclusions: As a result of this study, it is necessary to implement a program to reduce the HAV exposure levels.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.4
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• pp.177-183
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• 2015

Incremental sheet metal forming is a manufacturing process to produce thin parts using sheet metals by a series of small incremental deformation. The process rarely needs dedicated dies and molds, thus, preparation time for the process is relatively short as to be compared to conventional metal forming. Spring back in sheet metal working is very common, which causes critical errors in dimensions. Incremental sheet metal forming is not fully investigated yet. Hence, incremental sheet metal forming frequently produces inaccurate parts. This paper proposes a method to minimize dimensional errors to improve shape accuracy of products manufactured by incremental forming. This study conducts experiments using an exclusive incremental forming machine and the material for these experiments are sheets of aluminum AL1015. This research defines a process parameter and selects a few factors for the experiments. The parameters employed in this paper are tool feed rate, tool diameter, step depth, material thickness, forming method, dies applied, and tool path method. In addition, their levels for each factor are determined. The plan of the experiments is designed using orthogonal array $L_8$ ($2^7$) which requires minimum number of experiments. Based on the measurements, dimensional errors are collected both on the tool contacted surfaces and on the non-contacted surfaces. The distances between the formed surfaces and the CAD models are scanned and recorded using a commercial software product. These collected data are statistically analyzed and ANOVAs (analysis of variances) are drawn up. From the ANOVAs, this paper concludes that the process parameters of tool diameter, forming depth, and forming method are the significant factors to reduce the errors on the tool contacted surface. On the other hand, the experimental factors of forming method and dies applied are the significant factors on the non-contacted surface. However, the negative forming method always produces better accuracy than the positive forming method.