• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.247-250
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• 1995

The development and empirical validation of a mathematical model for predicting the depth of deformed layer in a machined surface are presented. The main assumption for develioping this model is that there is a linear relationship between plastic strain and the depth to which it extends. The model relates the work required to shear the workpice material to the work needed to compress the workpiece material ahead of the cutting tool. The results show that the percent difference between the calculated and the measured depth of deformed layer ranges form 4 percent to 19 percent. An improvement of the model is suggested through application of actual distribution data of plastic strain.

• International Journal of Safety
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• 제10권1호
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• pp.10-15
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• 2011

In Japan, protective measures to reduce falls from scaffolds have been strictly applied within industry safety guidelines, and such measures have significantly decreased fatal accidents due to falls from scaffolds. However, the rate of fatal accidents from falls is still high in the construction industries. In order to examine further countermeasures to reduce such falls, the Japan Ministry of Health, Labour and Welfare established a committee in our institute. That committee$\acute{i}$s work experimentally confirmed the effectiveness of using plastic sheets as a covering around scaffolds to protect against falls of construction materials (a method widely used in Japan). However, the workers fell from the space between the work platform and the plastic sheets very occasionally. Based on those results, the plastic sheets were improved for fall protection from the space, and the effect of the improved sheets was confirmed experimentally.

• Structural Engineering and Mechanics
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• 제71권3호
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• pp.223-232
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• 2019

Since the actuators with small- scale structures may be exposed to external reciprocal actions lead to create undesirable loads causing instability, the buckling behaviors of them are interested to make reliable or accurate actions. Therefore, the purpose of this paper is to analyze plastic buckling behavior of the micro beam structures by adopting a Conventional Mechanism-based Strain Gradient plasticity (CMSG) theory. The effect of length scale on critical force is considered for three types of boundary conditions, i.e. the simply supported, cantilever and clamped - simply supported micro beams. For each case, the stability equations of the buckling are calculated to obtain related critical forces. The constitutive equation involves work hardening phenomenon through defining an index of multiple plastic hardening exponent. In addition, the Euler-Bernoulli hypothesis is used for kinematic of deflection. Corresponding to each length scale and index of the plastic work hardening, the critical forces are determined to compare them together.

• Archives of Plastic Surgery
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• 제41권6호
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• pp.768-772
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• 2014

Background To compare clinical and radiographic outcomes between intramedullary nail fixation and percutaneous K-wire fixation for fractures in the distal third portion of the metacarpal bone. Methods A single-institutional retrospective review identified 41 consecutive cases of metacarpal fractures between September 2009 and August 2013. Each of the cases met the inclusion criteria for closed, extra-articular fractures of the distal third of the metacarpal bone. The patients were divided by the method of fixation (intramedullary nailing or K-wire). Outcomes were compared for mean and median total active motion of the digit, radiographic parameters, and period until return to work. Complications and symptoms were determined by a questionnaire. Results During the period under review, 41 patients met the inclusion criteria, and the fractures were managed with either intramedullary nailing (n=19) or percutaneous K-wire fixation (n=22). The mean and median total active range of motion and radiographic healing showed no statistically significant difference between the two groups. No union failures were observed in either group. The mean operation time was shorter by an average of 14 minutes for the percutaneous K-wire fixation group. However, the intramedullary nailing group returned to work earlier by an average of 2.3 weeks. Complications were reported only in the K-wire fixation group. Conclusions Intramedullary nailing fixation is advisable for fractures in the distal third of the metacarpal bone. It provides early recovery of the range of motion, an earlier return to work, and lower complication rates, despite potentially requiring a wire removal procedure at the patient's request.

• Earthquakes and Structures
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• 제11권5호
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• pp.823-840
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• 2016

The plastic hinge lengths of beams and columns are a critical demand parameter in the nonlinear analysis of structures using the finite element method. The numerical model of a plastic hinge plays an important role in evaluating the response and damage of a structure to earthquakes or other loads causing the formation of plastic hinges. Previous research demonstrates that the plastic hinge length of reinforced concrete (RC) columns is closely related to section size, reinforcement ratio, reinforcement strength, concrete strength, axial compression ratio, and so on. However, because of the limitations of testing facilities, there is a lack of experimental data on columns with large section sizes and high axial compression ratios. In this work, we conducted a series of quasi-static tests for columns with large section sizes (up to 700 mm) and high axial compression ratios (up to 0.6) to explore the propagation of plastic hinge length during the whole loading process. The experimental results show that besides these parameters mentioned in previous work, the plastic hinge of RC columns is also affected by loading amplitude and size effect. Therefore, an approach toward considering the effect of these two parameters is discussed in this work.

• Journal of Welding and Joining
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• 제18권5호
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• pp.84-89
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• 2000

Friction welding of titanium and aluminium is numerically modeled by the axisymmetric thermal elastic-plastic analysis. In titanium/aluminium friction welding, heat transfers into the titanium substrate to a distance of z=10(mm) on the side of the bondline and into the whole region of the aluminium substrate having the large thermal conductivity. Adjacent to the bondline, $^{\sigma}r\;and\;^{\sigma\theta}$ are tensile in the substrate whose thermal shrinkage is large, and are compressive in the substrate whose thermal shrinkage is small. $\sigma_z$ along the radial direction is large tensile at the periphery of the component. Plastic strain occurs only close to the bondline in the aluminium substrate. In the components of plastic strain, $\varepsilon^p_r\;and\;\varepsilon^p_{\theta}$ have positive values and $\varepsilon^p_r$ has large negative value. However, $\varepsilon^p_r$ is produced not because of the severity of the mechanical restraint condition, but on purpose to satisfy the condition of the volume constant. A plastic work is proposed as a measure to evaluate the mechanical severity. The plastic work is larger in the aluminium substrate than that in the titanium substrate. The mechanical condition is severer in the aluminium substrate.

• Archives of Plastic Surgery
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• 제44권6호
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• pp.573-574
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• 2017

When a newly inducted plastic surgery resident embarks on maxillofacial surgery, with drills, screws, plates and burrs, it seems like a new domain altogether. As a new resident, it is truly fascinating as to how such wide variety of bony work is done without scarring over the face. Here we discuss a few practical tips which the author has learned during his surgical sojourn in residency. It is hoped that the readers who are new to maxillofacial surgery, shall find these useful.

• Archives of Plastic Surgery
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• 제45권2호
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• pp.99-101
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• 2018

Revising manuscripts is often challenging and may be a task that authors do not want to face, but it is a crucial step for significantly improving authors' work before the final publication. Understanding these general rules and the several tips discussed above may be helpful for authors in dealing with comments from editors and reviewers.

• Structural Engineering and Mechanics
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• 제16권1호
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• pp.47-62
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• 2003

The nonlinear dependence aspect of various conical tool indentation parameters leading to an optimum tool semi angle value for easiest perforation is plotted and discussed explicitly in this work with the conclusion that tool angle has an optimum response towards most of the indentation parameters. Around this optimum angle, the aluminium sheets showed minimum fracture toughness as well as minimum work input to overcome the offered resistance. At the end, the mechanism leading to this phenomenon is presented with the conclusion that plastic flow dominates as the dimple semi cone angle reaches 35 and both pre and post plastic flow perforations lead the tool semi cone angle value towards this dimple cone semi angle of plastic flow initiation for its optimum performance. It is also concluded that specimen material failure is solely under tensile hoop stress and hence results into radial cracks initiation and propagation.

• Archives of Plastic Surgery
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• 제49권5호
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• pp.563-568
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• 2022

Rhinoplasty is one of the first surgical procedures described with evidence in the history of medicine. At first, these were performed for the reconstruction of traumatic defects caused by punishments, sequels of war, and then it had been reused after suffering from diseases such as syphilis. Many techniques have been developed from the need of aesthetics outcomes in this field. The objective of our work is to describe a modified approach of recycled dorsum preservation procedure that we have proposed as a safe and reliable technique. In this work, we have showed that this technique has a marked advantage of preserving the natural tissue with satisfactory postoperative result. We had no functional complications up to date. We recommend that every specialist in the field of rhinoplasty should be able to use it as a reproducible and feasible alternative.