• 한국정밀공학회지
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• 제6권4호
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• pp.94-102
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• 1989

The effect of plastic strain on the surface integrity of mild steel (SS 41) was studied. This paper shows that the recrystallization technique is adequate to evaluate the plastic strain in a machined surface experimentally. The relations between the plastic strain and the machining conditions are quantitatively evaluated by using the recrystallization technique. The obtained results are summarized as follows. 1. The surface integrity of steel is considerably influenced by the amount of surface region deformation produced by changes in cutting conditions. 2. The plastic strain in machined surface produced by changes of the cutting conditions is evaluated by the recyrstallization technique. 3. The plastic strain increases with the increase of depth of cut and the decrease of rake angle. 4. When the cutting force is high and the rake angle is small, the value of maximum true strain reaches to high. 5. The maximum true strain is related to the cutting energy, and the values increase with the increase of the unit shear and total engergy in constant depth with the increase of the energy values.

• Advances in concrete construction
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• 제10권4호
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• pp.319-332
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• 2020

The impacts of reinforcing concrete matrix with steel fibers, polypropylene fibers and recycled plastic fibers using different volume fractions of 0.15%, 0.5%, 1.5% and 2.5% on the compressive and tensile characteristics are experimentally investigated in the current research. Also, flexural behavior of plain concrete (PC) beams, shear performance of reinforced concrete (RC) beams and compressive characteristics of both PC and RC columns reinforced with recycled plastic fibers were studied. The experimental results showed that the steel fibers improved the splitting tensile strength of concrete higher than both the polypropylene fibers and recycled plastic fibers. The end-hooked steel fibers had a positive effect on the compressive strength of concrete while, the polypropylene fibers, the recycled plastic fibers and the rounded steel fibers had a negative impact. Compressive strength of end-hooked steel fiber specimen with volume fraction of 2.5% exhibited the highest value among all tested samples of 32.48 MPa, 21.83% higher than the control specimen. The ultimate load, stiffness, ductility and failure patterns of PC and RC beams in addition to PC and RC columns strengthened with recycled plastic fibers enhanced remarkably compared to non-strengthened elements. The maximum ultimate load and stiffness of RC column reinforced with recycled plastic fibers with 1.5% volume fraction improved by 21 and 15%, respectively compared to non-reinforced RC column.

• Computers and Concrete
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• 제19권6호
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• pp.689-699
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• 2017

An energy-based approach for determining earthquake safety of reinforced concrete frame structures is presented. The developed approach is based on comparison of plastic energy capacities of the structures with plastic energy demands obtained for selected earthquake records. Plastic energy capacities of the selected reinforced concrete frames are determined graphically by analyzing plastic hinge regions with the developed equations. Seven earthquake records are chosen to perform the nonlinear time history analyses. Earthquake plastic energy demands are determined from nonlinear time history analyses and hysteretic behavior of earthquakes is converted to monotonic behavior by using nonlinear moment-rotation relations of plastic hinges and plastic axial deformations in columns. Earthquake safety of selected reinforced concrete frames is assessed by using plastic energy capacity graphs and earthquake plastic energy demands. The plastic energy dissipation capacities of the frame structures are examined whether these capacities can withstand the plastic energy demands for selected earthquakes or not. The displacements correspond to the mean plastic energy demands are obtained quite close to the displacements determined by using the procedures given in different seismic design codes.

• Journal of Electrical Engineering and Technology
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• 제2권1호
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• pp.112-117
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• 2007

a parametric investigation was conducted to evaluate the effect of the laser beam for plastic adhesion. To determine the best condition for plastic adhesion, the $CO_2$(wavelength $10.6{\mu}m$) and nd:yag(wavelength $10.6{\mu}m$) laser were experimented with. From the experiment results obtained, the nd:yag laser was revealed to be the most suitable for plastic adhesion. In this study, three adhesion parameters such as input power level, working time of laser beam and pps(pulse per second) were systematically adjusted for suitable adhesion. From these experiments, it was observed that the target plastic melted and was evaporated by the nd:yag laser. Furthermore, the relationships between adhesive surface by laser beam and above three parameters were discovered.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 춘계학술대회 논문집
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• pp.151-154
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• 2002

In this paper, the effect of the crack growth length on the plastic zone size at the crack tip and the crack growth lives of the DENT specimen under constant amplitude cyclic loading were studied. The plastic zone size was calculated by nonlinear static method in commercial finite element analysis program, MSC/NASTRAN and the crack growth lives were also calculated by using compliance function considering geometric shape in MSC/FATIGUE. The calculated plastic zone size increased proportional to the crack length. And comparison of calculated plastic zone size and crack growth lives with the experimental results shows a good agreement.

• 방사선산업학회지
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• 제10권4호
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• pp.167-171
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• 2016

The scintillation efficiency of the polystyrene based plastic scintillator depends on the ratio of the wavelength shifters, organic fluors(PPO and POPOP). Thus, 24 samples of the plastic scintillator were fabricated in order to find out the optimum ratio of the wavelength shifters in the plastic scintillator. The fabricated plastic scintillators were trimmed through a cutting and polishing process. They were used in gamma energy spectrum measurement with the $^{137}Cs$ emitting mono-energy photon with 662 keV for the comparison of the scintillation efficiency. As a result, it was found out that the scintillator sample with 1.00 g of PPO (2,5-Diphenyloxazole) and 0.50 g of POPOP (1,4-Bis(5-phnyl-2oxidazolyl)benzene) dissolved in 100 g of styrene solution has the optimum ratio in terms of the light yield of the polystyrene based plastic scintillator.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.988-1003
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• 2021

Existing elastic analysis methods cannot be adhered to in order to assess the structural integrity of a reactor vessel and internals for a beyond design basis earthquake. Elasto-plastic analysis methods are required, and the factors that affect the elasto-plastic behavior of reactor materials should be taken into account. In this study, a material behavior model was developed that considers the irradiation embrittlement effect, which affects the elasto-plastic behavior of the reactor material. This was used to perform the elasto-plastic time history analyses of the reactor vessel and its internals for beyond design basis earthquake. For this investigation, appropriate beyond design basis earthquakes and reliable finite element models were used. Based on the analysis results, consideration was given to the load reduction effect and the margin change. These were transferred to the internals due to the plastic deformation of the reactor vessel.

• 한국폐기물자원순환학회지
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• 제35권8호
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• pp.709-720
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• 2018

Since the import ban of plastic waste in China has been enforced, plastic wastes were not properly collected and recycled in Korea. Hence, the management strategies for plastic waste in Korea should be improved by examining the regulations and policy in developed countries such as United States, Japan, EU and United Kingdom. The management strategy for the recycling cycle should be implemented to expand the labeling system of separation and discharge, reduce the consumption of plastic products, automate the separation and sorting method in recycling facilities, and improve the economical efficiency of the recycling cycle. The concept of residual waste (secondary waste) in the material flow analysis should be implemented to identify the shortage point in the plastic waste stream. Finally, the cooperation with international communities is required for a transboundary movement of plastic waste, which includes participation at the working group of international standards to recycle plastic waste.

• Earthquakes and Structures
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• 제8권3호
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• pp.619-637
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• 2015

A field based non-destructive hardness method is being developed to determine plastic strain in steel elements subjected to seismic loading. The focus of this study is on the active links of eccentrically braced frames (EBFs). The 2010/2011 Christchurch earthquake series, especially the very intense February 22 shaking, which was the first earthquake worldwide to push complete EBF systems into their inelastic state, generating a moderate to high level of plastic strain in EBF active links for a range of buildings from 3 to 23 storeys in height. Plastic deformation was confined to the active links. This raised two important questions: what was the extent of plastic deformation and what effect does that have on post-earthquake steel properties? A non-destructive hardness test method is being used to determine a relationship between hardness and plastic strain in active link beams. Active links from the earthquake affected, 23-storey Pacific Tower building in Christchurch are being analysed in the field and laboratory. Test results to date show clear evidence that this method is able to give a good relationship between plastic strain and demand. This paper presents significant findings from this project to investigate the relationship between hardness and plastic strain that warrant publication prior to the completion of the project. Principal of these is the discovery that hot rolled steel beams carry manufacturing induced plastic strains, in regions of the webs, of up to 5%.

• 자원리싸이클링
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• 제27권4호
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• pp.3-15
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• 2018

플라스틱은 용기, 포장재, 필름 등 다양한 분야에서 사용이 증가하고 있으며, 플라스틱 사용의 증가에 따라 폐플라스틱의 발생도 증가하고 있는 추세이다. 국내의 폐플라스틱은 폐기물 부담금, 생산자책임재활용제도와 자발적 협약 등의 제도에 의하여 관리되고 있다. 최근 폐플라스틱 수거업체에서의 수거 거부에 의한 문제에 대응하기 위하여 환경부에서는 제조 생산 - 분리 배출 - 수거 선별 - 재활용의 순환주기에 따른 재활용 폐기물 관리 종합대책을 발표하였다. 이러한 폐플라스틱 관리에 대하여 국내 폐플라스틱 관리현황과 환경부의 대책을 검토하여 폐플라스틱의 순환주기에 따른 개선방안을 제시하였다.