• Structural Engineering and Mechanics
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• 제58권4호
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• pp.719-729
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• 2016

The main objective of the present paper is to study the effect of the yield criterion on the magnitude of the strain rate and plastic work rate intensity factors in axisymmetric flow of isotropic incompressible rigid perfectly plastic material by means of a problem permitting a closed-form solution. The boundary value problem consisting of the axisymmetric deformation of a plastic tube is solved. The outer surface of the tube contracts. The radius of the inner surface does not change. The material of the tube obeys quite a general yield criterion and its associated flow rule. The maximum friction law is assumed at the inner surface of the tube. Therefore, the velocity field is singular near this surface. In particular, the strain rate and plastic work rate intensity factors are derived from the solution. It is shown that the strain rate intensity factor does not depend on the yield criterion but the plastic work rate intensity factor does.

• 한국의류학회지
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• 제17권1호
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• pp.19-35
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• 1993

This study was designed to devise work wear for plastic house worker. It was carried out (1) research on the clothing actual condition through interviewings with plastic house worker and observations, (2) thermal manikin test to measure thermal resistance of experimental clothes and (3) clothing comparing test in the laboratory and in the plastic house. In the laboratory experiment, it was choosen general type (A) and new devised types (B, C) made of microporous fabric for experimental clothes. Experimental clothes were made of 6 combinations including 3 type work wears (A, B, C) and 2 type underwears (1, 2). In the plastic house experiment, it was choosen general types of A (without rest place) and B (with rest place), and devised type C (with rest place), which was appeared good effect in the laboratory experiment. The results were as followings. 1. Work environment of the plastic house in summer and winter was very different from the outer environment. Work motion in the plastic house was burden to the plastic house workers. 2. Plastic house workers had on the general type's work wear. 3. As a result of thermal manikin test, thermal resistance was appeared B1>B2>C2>C1>A1>A2 in orders. 4. In the laboratory experiment, experimental clothes A was appeared smaller burden than B, C. Effect of mesh underwear was not appeared in this study condition. In subjective sensation, experimental clothes C was lower vote than A. Therefore experimental clothes C was superior to A in subjective wearing sensation. 5. In the plastic house experiment, the experimental conditions with rest place were appeared smaller burden than without rest place. General type B was appeared more positive physiological reactions than devised type C but significances between two types was not appeared.

• 한국농촌생활과학회지
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• 제5권2호
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• pp.107-115
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• 1994

This study was conducted to provide a counterplan for preventing so celled “plastic house syndrome” revealed among farmers spending much time in the plastic houses. For this, working environment inside a plastic house was observed. Then, experiments were carried out mostly in a climatic chamber with three kinds of working posture on uneven($D_1-F_1$) or even($D_2-F_2$) ground surface. Tested work loads with three kinds of working posture were : moving in a sitting posture with attaching breast to legs and waving arms ($A_1$), moving in a bending posture with waving arms ($B_1$), and moving a 6kg weighting luggage in a standing posture ($C_1$) Physiological responses in the workers to three different work loads were observed in a climatic chamber, with or without using some instruments, to evaluate work efficiencies. The results obtained are summerized as follows. 1. $C_1$ was the hardest work and $B_1$ was harder than $A_1$ on the even ground. 2. Worker's physiological fatigue and physical loads remarkably decreased when using the instruments such as a chair and a cart with some rollers on the even ground. 3. Working with pushing a cart($F_1$) was the hardest work, and standing($D_1$) was harder than walking($E_1$) on the uneven ground. 4. Worker's physiological fatigues and physical loads remarkably decreased on the even ground. 5. Similar results were obtained when the same experiment was carried out in a plastic house.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.1041-1044
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• 1996

The plastic-film-covered hill planter is a new-type seeding machine, including tow types which are mounted by 11kw and 40 kw tractors. It is made up of fertilizing , plastic-film covering perforating film and hole seeding, soil sealing apparatus, and can work at 5-7kw/h. The plastic-film covering and seeding of cotton, corn and soybean can all use this machine. The plastic-film-covered hill planter is mainly composed of plastic film covering unit, drum-type hill-drop unit and furrow coverer, some other types are also equipped with fertilizer drill unit. It can do combined work of covering plastic film , sowing , plastic film perforating , soil covering at one time, and it is suitable to the covering plastic film as well as planting of the grandulated crops, such as cotton , corn, soybean and so on.

• Archives of Plastic Surgery
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• 제48권4호
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• pp.384-388
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• 2021

Adequate positioning of the hand is a critical step in hand fracture operative repair that can impact both the clinical outcome and the efficiency of the operation. In this paper, we introduce the use of a thermoplastic splint with an added thumb stabilizing component as a means to increase the surgeon's autonomy and to streamline the patient care pathway. The thermoplastic splint is custom fabricated preoperatively by the specialist hand therapist. The splint is used prior, during, and post operation with minimal modification. The thumb component assists maintaining the forearm in a stable pronated position whilst drilling and affixing metal work. This is demonstrated in the video of removal of metal work and open reduction and internal fixation of a metacarpal fracture.

• 산업경영시스템학회지
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• 제18권34호
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• pp.35-42
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• 1995

In the plastic extrusion process, product quality is influenced by work condition for temperature of cylinders and dies. The work conditions are various, so it is difficult to standardization of the work conditions. Therefore, the work conditions are depended on the workers of experience and skill. In the plastic extrusion process, it has five control heating points on the cylinder and three control heating points on the die. In addition, there is one control point on the extrusion process. It is extrusion speed. In this case, we don't know how these affect product quality. We structure the multiple linear regression equation with the temperature of cylinders and dies as independent variables and the product weight as dependent variable. We solve this equation using statistic computer package named Juse-Qcas.

• 자원리싸이클링
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• 제11권3호
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• pp.37-45
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• 2002

마찰대전 분리는 서로 상이한 두 물체를 마찰시켜 각자 반대극성으로 하전시킨 후 전기장에 통과시켜 분리하는 기술이며, 이때자 물질의 하전극성은 work function에 의해 각기 다른 극성으로 하전된다. 본 연구에서는 마찰대전을 이용한 정전분리에 기본이 되는 각종 플라스틱의 work function을 알아보는 데 중점을 두었으며 마찰대전 후 하전량에 따른 분리 효율을 도출하여 최적의 운전조건을 위한 하전특성을 알아보았다. 플라스틱 시료는 2가지의 샘플을 가지고 실험하였으며. 이를 각기 다른 재질의 드럼형 마찰하전장치를 이용하여 대전을 시켰다. 또한 Faraday Cage를 이용하여 하전량을 측정한 후 work function을 도출하였다. 하전된 입자는 $\pm$20 kV의 전장에 통과시켜 분리실험을 수행하고 이를 통해서 하전량과 분리효율간의 상관관계를 도출하였다.

• Steel and Composite Structures
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• 제8권1호
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• pp.85-98
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• 2008

In this study the progressive collapse potential of three- and nine-story special steel moment frames designed in accordance with current design code was evaluated by nonlinear static and dynamic analyses. It was observed that the model structures had high potential for progressive collapse when a first story column was suddenly removed. Then the size of beams required to satisfy the failure criteria for progressive collapse was obtained by the virtual work method; i.e., using the equilibrium of the external work done by gravity load due to loss of a column and the internal work done by plastic rotation of beams. According to the nonlinear dynamic analysis results, the model structures designed only for normal load turned out to have strong potential for progressive collapse whereas the structures designed by plastic design concept for progressive collapse satisfied the failure criterion recommended by the GSA guideline.

• Structural Engineering and Mechanics
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• 제63권1호
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• pp.23-35
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• 2017

A nonlinear static procedure considering work-energy principle and global failure mechanism to estimate base shears of reinforced concrete (RC) frame-type structures is presented. The relative energy equation comprising of elastic vibrational energy, plastic strain energy and seismic input energy is obtained. The input energy is modified with a factor depending on damping ratio and ductility, and the energy that contributes to damage is obtained. The plastic energy is decreased with a factor to consider the reduced hysteretic behavior of RC members. Given the pre-selected failure mechanism, the modified energy balance equality is written using various approximations for modification factors of input energy and plastic energy in scientific literature. External work done by the design lateral forces distributed to story levels in accordance with Turkish Seismic Design Code is calculated considering the target plastic drift. Equating the plastic energy obtained from energy balance to external work done by the equivalent inertia forces considering, a total of 16 energy-based base shears for each frame are derived considering different combinations of modification factors. Ductility related parameters of modification factors are determined from pushover analysis. Relative input energy of multi degree of freedom (MDOF) system is approximated by using the modal-energy-decomposition approach. Energy-based design base shears are compared with those obtained from nonlinear time history (NLTH) analysis using recorded accelerograms. It is found that some of the energy-based base shears are in reasonable agreement with the mean base shear obtained from NLTH analysis.

• 소성∙가공
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• 제14권4호
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• pp.327-337
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• 2005

In the present work, the two back stress kinematic hardening models are proposed by combining Armstrong-Frederick, Phillips and Ziegler's hardening rules. Simple combination of hardening rules using simple rule of mixtures results in various evolutions of the kinematic hardening parameter. Using the combined hardening models the ultimate back stress fur the present models is also derived. The stress rate is co-rotated with respect to the spin of substructure due to the assumption of kinematic hardening rule in finite deformation regime. The work piece under consideration is assumed to consist of the elastic and the rigid plastic deformation zone. Then, the J2 deformation theory is facilitated to characterize the plastic deformation behavior under various loading conditions. The plastic deformation localization behaviors strongly depend on the constitutive description namely back stress evolution and its hardening parameters. Then, the analysis for Swift's effects under the fixed boundaries in axial directions is carried out using simple shear deformation.