• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.2
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• pp.107-114
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• 2024

Objectives: This study was performed to evaluate the musculoskeletal symptoms of workers treating electronics industry waste at a recycling sorting plant by case survey. Methods: The musculoskeletal symptoms were investigated by conducting a survey targeting workers treating waste from the electronics industry. Through utilizing the ergonomic evaluation techniques such as RULA, REBA, and OWAS, the four tasks were divided into three detailed processes (sorting, movement, loading) and the work of workers was evaluated for a total of 12 processes. Results: As a result of the questionnaire survey on musculoskeletal symptom, 40% of workers answered that they had musculoskeletal disease symptoms, and the symptom sites were hands(30%), legs(20%), arms(10%), and shoulders(5%). Based on the results obtained from analysis through ergonomic evaluation techniques such as RULA, REBA, and OWAS, 75% of them were found to need improvement or follow-up immediately or immediately after the second stage or higher. As compared to REBA and OWAS, the RULA, which evaluates the upper limb in detail, has a higher score, and in the process of sorting and loading relatively light wastes such as paper and plastic, the waist is raised by repeating the work of bowing and stretching. Conclusions: The heavy wastes such as 200L drums were evaluated as having a low load on the elbows and wrists because body action was relatively lower than moving paper and plastic. In addition, the overall load score was evaluated lower in the moving work compared to the sorting or loading process.

• Transactions of Materials Processing
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• v.7 no.3
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• pp.233-245
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• 1998

A new approach has been proposed for the incremental analysis of the nonsteady state large deformation of planar anisotropic elastic-plastic sheet forming. A mathematical brief review of a constitutive law for the incremental deformation theory has been presented from flow theory using the minimum plastic work path for elastic-plastic material. Since the material embedded coordinate system(Lagrangian quantity) is used in the proposed theory the stress integration procedure is completely objective. A new return mapping algorithm has been also developed from the general midpoint rule so as to achieve numerically large strain increment by successive control of yield function residuals. Some numerical tests for the return mapping algorithm were performed using Barlat's six component anisotropic stress potential. Performance of the proposed algorithm was shown to be good and stable for a large strain increment, For planar anisotropic sheet forming updating algorithm of planar anisotropic axes has been newly proposed. In order to show the effectiveness and validity of the present formulation earing simulation for a cylindrical cup drawing and front fender stamping analysis are performed. From the results it has been shown that the present formulation can provide a good basis for analysis for analysis of elastic-plastic sheet metal forming processes.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.3
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• pp.19-28
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• 1995

The explicit scheme for finite element analysis of sheet metal forming problems has been widely used for providing practical solutions since it improves the convergency problem, memory size and computational time especially for the case of complicated geometry and large element number. The explicit schemes in general use are based on the elastic-plastic modelling of material requiring large computation time. In the present work, rigid-plastic explicit finite element method is introduced for analysis of sheet metal forming processes in which plane strain normal anisotropy condition can be assumed by dividing the whole piece into sections. The explicit scheme is in good agreement with the implicit scheme for numerical analysis and experimental results of auto-body panels. The proposed rigid-plastic explicit finite element method can be used as robust and efficient computational method for prediction of defects and forming severity.

• Transactions of Materials Processing
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• v.19 no.8
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• pp.502-507
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• 2010

The physical and mechanical properties and formability of sheet metals depend on preferred crystallographic orientations (texture). In this research work, the texture development and formability (plastic strain ratios) of AA1050 Al alloy sheets after 3 and 10 passes of asymmetric rolling and subsequent heat treatment were investigated. The plastic strain ratios of 10 passes asymmetrically rolled and subsequent heat treated samples are 1.3 times higher than those of the initial AA1050 Al alloy sheets. The ${\Delta}r$ of 10 passes of asymmetrically rolled and subsequent heat treated samples is 1/30 times lower than those of the initial AA1050 Al alloy sheets. The plastic strain ratios of 10 passes of asymmetrically rolled and subsequent heat treated Al sheets are higher than those of 3 passes ones. These results could be attributed to the formation of $\gamma$-fiber, ND//<111>, and the other texture components by means of asymmetric rolling in Al sheets.

• Steel and Composite Structures
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• v.26 no.4
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• pp.439-452
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• 2018

This paper presents experimental and numerical study on buckling behaviors and hysteretic performance of Class 1 H-shaped steel beam subjected to cyclic pure bending within the scope of ultra-low cycle fatigue (ULCF). A loading device was designed to achieve the pure bending loading condition and 4 H-shaped specimens with a small width-to-thickness ratio were tested under 4 different loading histories. The emphasis of this work is on the impacts induced by local buckling and subsequent ductile fracture. The experimental and numerical results indicate that the specimen failure is mainly induced by elasto-plastic local buckling, and is closely correlated with the plastic straining history. Compared with monotonic loading, the elasto-plastic local buckling can occur at a much smaller displacement amplitude due to a number of preceding plastic reversals with relative small strain amplitudes, which is mainly correlated with decreasing tangent modulus of the material under cyclic straining. Ductile fracture is found to be a secondary factor leading to deterioration of the load-carrying capacity. In addition, a new ULCF life evaluation method is proposed for the specimens using the concept of energy decomposition, where the cumulative plastic energy is classified into two categories as isotropic hardening and kinematic hardening correlated. A linear correlation between the two energies is found and formulated, which compares well with the experimental results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.528-535
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• 2011

In the present, the formation of shear band under a simple shear deformation is investigated using a rate-independent elastic-plastic constitutive relations. Moreover, the strain gradient terms are incorporated to obtain a non-local plastic constitutive relation, which in turn represented using combined two-back stress hardening model. Then, the continuum damage model is also included to the proposed model. The post-localization behavior are studied by introducing a small imperfection in a work piece. The strain gradient affects the shear localization significantly such that the intensity of shear band decreases as the strain gradient coefficient increases when the J2 flow theory is employed.

• Steel and Composite Structures
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• v.11 no.2
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• pp.131-147
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• 2011

The aim of this work is to provide some insights into the elasto-plastic behaviour of plate girder web square and rectangular panels with centred and eccentric holes under both compression and in-plane bending moment. The numerical study was validated comparing the numerical results obtained for one simple steel plate configuration with the corresponding experimental results, obtained at the University of Padova, observing the influence of the initial out-of-plane imperfections on the force vs. displacement relationship and ultimate strength. Once validated the numerical approach, the effect of bending moment on the stability of the plate is studied and some differences with respect to the uniform compression load case are shown. The influence of dimension and position of the hole, the plate aspect ratio and the steel grade on elasto-plastic behaviour is observed. Some indications regarding the critical slenderness (at which transition from elastic to plastic collapse occurs) are given for square and rectangular plates with symmetric and eccentric holes having small, medium and large diameter.

• Journal of the Korean Society of Costume
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• v.52 no.3
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• pp.61-73
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• 2002

The purpose of this study lies in pursuing the unique plastic arts with the orchid motif which has the graceful colors and a variety of shapes beauty. Another aspect of this study intends to crease the modern costume design with the high added value by expressing the texture according to the material and tissue development for the continual improvement and promotion of the modern costume design in the handicraft art area. The results through the theoretical survey and the work production are as follows : First, the orchid which has the various shapes and colors provides the designers with the unique plastic arts and the possibilities for the unlimited expressions as the design motives. Second, we can see the creation of cubic plastic beauty in the moving line, as the material which has the flexible and brilliant shape fixation, used for expressing the shape beauty of the orchid. Third, this study reveals the extension of expression areas as a characteristic of the plastic arcs by applying handicraft techniques such as dyeing, corded tuck, flounce, crochet, weaving, beads embroidery, and art flower to the costumes for developing the unique material and texture. Finally, the possibility is suggested that the desires of the moderns searching for their own individualities can be met by creating the costumes with the added vague as the exposure of esthetic consciousness through the handicraft expression techniques.

• Archives of Plastic Surgery
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• v.42 no.1
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• pp.73-77
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• 2015

The latissimus dorsi flap is popular due to the versatile nature of its applications. When used as a pedicled flap it provides a robust solution when soft tissue coverage is required following breast, thoracic and head and neck surgery. Its utilization as a free flap is extensive due to the muscle's size, constant anatomy, large caliber of the pedicle and the fact it can be used for functional muscle transfers. In facial palsy it provides the surgeon with a long neurovascular pedicle that is invaluable in situations where commonly used facial vessels are not available, in congenital cases or where previous free functional muscle transfers have been attempted, or patients where a one-stage procedure is indicated and a long nerve is required to reach the contra-lateral side. Although some facial palsy surgeons use the trans-axillary approach, an operative guide of raising the flap by this method has not been provided. A clear guide of raising the flap with the patient in the supine position is described in detail and offers the benefits of reducing the risk of potential brachial plexus injury and allows two surgical teams to work synchronously to reduce operative time.

• Geomechanics and Engineering
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• v.21 no.1
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• pp.73-84
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• 2020

In the seismic design of bridges, formation of plastic hinges plays an important role in the dissipation of seismic energy. In the case of conventional fixed-base bridges, the plastic hinges are allowed to form in the superstructure alone. During seismic event, such bridges may be safe from collapse but the superstructure undergoes significant plastic deformations. As an alternative design approach, the plastic hinges are guided to form in the soil thereby utilizing the inevitable yielding of the soil. Rocking foundations work on this concept. The formation of plastic hinges in the soil reduces the load and displacement demands on the superstructure. This study aims at evaluating the seismic response of bridge pier supported on rocking shallow foundation. For this purpose, a BNWF model is implemented in OpenSees platform. The capability of the BNWF model to capture the SSI effects, nonlinear behavior and dynamic loading response are validated using the centrifuge and shake table test results. A comparative study is performed between the seismic response of the bridge pier supported on the rocking shallow foundation and conventional fixed-base foundation. Results of the study have established the beneficial effects of using the rocking shallow foundation for the seismic response analysis of the bridge piers.