• The Journal of the Korea Contents Association
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• v.12 no.9
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• pp.389-395
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• 2012

This research analyzed the peak impulsive force, maximum velocity and a spot of fist's maximum velocity comparing stop-jirugi and push-jirugi. 7 males volunteered for this experiment. peak impulsive force was measured by PS2142 force platform[10], and maximum velocity of fist was measured by PS2103A motion sensor[12]. All of data was collected in the data studio and t-test was applied using SAS 9.1 package. The following conclusions were drawn. First, stop-jirugi's peak impulsive force was greater (P<.01) than that of push-jirugi. Second, push-jirugi's maximum velocity of fist was greater (P<.01) than that of stop-jirugi. Third, stop-jirugi's maximum velocity of fist was occurred on 69.14% of arm's length and that of push-jirugi was occurred on 75.66%. This maximum velocity spot was statistically significant difference(p<.001).

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.4
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• pp.209-214
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• 2011

Objectives: To assess the risk of pushing or pulling the yarn-carrying cart, the survey was performed in some fiber manufacturing factories. Methods: We selected 6 fiber-twisting factories which agreed to in-site survey of their workplace. To measure both initial and sustained forces of the push-pull tasks, Chatillon CSD500 dynamometer(2004, Ametek, USA) was used. The mean of 3 tests for the same cart was adopted as the measured forces. Height and width of cart, weight of spooled yarns, and distance of movement were also measured. Inspection of cart wheel, moving path, and the actual hand position while moving was done. Results: More than one pushing or pulling task exceeded the push-pull force limits of design goal in 5 factories. Though the cart was not loaded the heaviest weight in the factory, the measured push or pull force exceeded the limits several times. A few cart wheels were worn out and tangled with pieces of yarn. It was also observed some holes in the moving path. Conclusions: While the push-pull task is not included in the 11 scopes of over-burdened work notified by Korean government, it should be recognized as risk factor of work-related musculoskeletal disorders. The maintenance work such as regular change and frequent cleaning of cart wheel, the use of fitting wheel, and flattening of bumpy floor through the moving path should be advised importantly in the worksite management of work-related musculoskeletal disorders.

• Journal of the Ergonomics Society of Korea
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• v.32 no.4
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• pp.405-411
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• 2013

Objective: Product design process without considering the strength of the user can cause the excessive burden on musculoskeletal system of human body. Since the muscle strength will vary depending on the body posture, the design of product should consider the characteristics of body posture. This study was performed to investigate the effects of forearm postures on the push and pull strength. Background: Overexerted force has been identified to cause musculoskeletal disorders. It is important to know the push and pull strength exerted by human when designing so that exerted force does not exceed the safety limits. Method: Maximum isometric push and pull strength of left, right and both hands were measured according to forearm postures with pronation, neutral and supination. For the study, 66 male and 30 female undergraduate students were participated as subjects. All subjects were normal and healthy with no clinical history. Results: The results showed that the push strength of male and female were 93.3% and 85.4% of pull strength. It showed that the strength of one-hand was 72.1~81.0% of the strength of two-hands, and the strength of left hand was 93.1~95.8% of the strength of right hand. The strength of female was 62% of the one of male. It was found that the strength with pronation $90^{\circ}$ was reduced up to 20% compared to the strength with neutral posture. Conclusion: Push and pull strength of male and female were reduced when forearm was rotated extremely. Application: The results of this study will be used for the prevention of work related musculoskeletal disorders and design of industrial equipment.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.4
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• pp.277-283
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• 2017

In this study, we investigated how a jumping strategy changes with an increase in the vertical jump height for a resultant ground reaction force (GRF) vector. We expected that the resultant force vector between two sequential motion phases (i.e., countermovement and push-off) of the countermovement jump would significantly change with the vertical jump height to take advantage of the resulting supportive force (i.e., an initial push-off force larger than the body weight) through the countermovement phase. Nine healthy young subjects were instructed to jump straight up to five different height levels ranging from 191 cm to 221 cm, and the kinematic and kinetic data were obtained in regular trials. The results showed that a lower center of mass position and larger resultant force vector were clearly observed in a higher jump, implying that the countermovement strategy changed with the vertical jump height to prepare for sufficient joint deviation and obtain a force advantage for larger push-off work.

• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.2
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• pp.131-137
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• 2000

In order to evaluate the design shear strength of composite slabs with truss-shaped shear connectors(TSC), a series of push-out tests on several types of specimens was carried out. The test results for the two parameters of bearing area and solid angle of the connector were compared to obtain the design shear force of the truss-shaped connectors. The results obtained from this study are as follows: (1) The slip-coefficients of TSC ranges from 0.87 to 3.12(${\times}10^6kgf/cm$). (2) The slip stiffness and the shear strength of TSC with $60.6cm^2$ bearing area are greater than those with $14.6cm^2$. (3) For estimating the allowable shear force of TSC, a design equation that is based on the bearing strength of the connector is suggested. (4) The mean safety factors of the critical force and the ultimate force are 2.38 and 4.62. respectively.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.04a
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• pp.48-51
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• 2008

Shear connector is the element which resist in the horizontal shear force between steel and concrete of composite members and the stud bolt is often used because of its constructional convenience and serviceability. Although the push-out test is the most common method to evaluate shear slip behaviour, it is suitable for only room temperature conditions. In this study, we investigated about shear force, temperature distribution and slip displacement of shear connector in high temperature through the modified push-out test with electronic furnace invented for steel part heating.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.93-94
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• 2016

The resistance of crowd pressure is an important performance to be influential on safety of facility users among performances required for light weight walls of public facilities. This study has empirically evaluated the estimation of size of crowd pressure to be applied to a wall of structure. For the load analysis test, the force plate with stiffness of 28 kN/cm was designed and manufactured. For inspectors, 15 males in the age of 20s were selected. The action of putting load was set as instantaneous push of plate and continuous push. As the load was increased linearly from the weight of inspector, the size of load was indicated as the load ratio. In case of instantaneous force, about 1.18 times the weight of pushing personnel was acted as a load. In case of continuous push, about 0.80 times the weight of pushing personnel was acted as a load.

• 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.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.01a
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• pp.141-142
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• 2017

기존의 상용화된 인체공학적 자세교정 의자나 의학적 치료 솔루션은 상대적으로 고가이며 사용자친화적인 접근성을 제공하기 어려웠다. 본 논문에서는 이 문제점을 해결하기 위해 소형 방석에 압력 센서를 접목하고 사용자에게 교정 상태를 상기시키는 시스템을 연구하고 이를 더 사용자 접근성이 좋은 방식을 고안하고자 한다. PushBullet[1] API를 사용하여 Non-Client Application 중심의 Multi-Device 기반 Push notification 기능을 연구하고 이와 기존의 바른 앉은 자세를 유지하는 자세교정 시스템을 결합한 방식을 제안한다.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.7
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• pp.307-314
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• 2001

A moving coil linear oscillatory actuator is consisted of the NdFeB permanent magnets with high specific energy as the stator, a coil-wrapped nonmagnetic hollow rectangular structure and an iron core as a pathway for magnetic flux. The variation of mover position and the consequent changes of coil flux path affect the coil inductance, because coil flux leaks at the open region of LOA stator. The interaction between permanent magnet and armature field is to shift the airgap flux density variation due to the magnet alone by a certain amount. The unbalanced reciprocation force due to armature reaction field decreases the advantage of moving coil LOA, such as a high degree of linearity and controllability in the force ad motion control. This paper firstly describes the coil inductance, the deviation of flux density, and the unbalanced reciprocation force, which are derived form the permeance model of LOA. Secondly, the analytical method are verified using the 2D finite element method and tests. Finally, the dynamic simulation algorithm taking the armature reaction effect and variable inductance into account, is proposed and confirmed through the experiment.