• Tribology and Lubricants
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• v.12 no.4
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• pp.18-27
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• 1996

An interlaboratory wear testing was performed in order to understand the friction behaviors and the wear mechanisms of the sintered composites. The specimens were the sintered bronze matrix composites having various contents of friction additives, friction control agents and reinforcements. The variation of the wear characteristics according to the constituents of the composites as well as the wear conditions was investigated by SEM, EPMA, OM, the hardness testing and the measurement of friction. The specimen having glass fiber as the matrix reinforcement showed a remarkable increase in wear resistance as increasing the content of glass fiber. Graphite particles in the composites exhibited the lubricating effect and also resulted in the lowering strength of the matrix. Addition of Mo powder to the composites led to the deterioration of wear properties at the room temperature, however, an enhanced wear properties were obtained in the containing Mo at an elevated temperature.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.4
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• pp.73-81
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• 2010

The cemented sand and gravel (CSG) method is a construction technique that adds cement and water to rock-like materials, such as rivered gravel or excavation muck which can be obtained easily at areas adjacent to dam sites. This study was performed to evaluate the compaction and compressive strength properties of stress-strain, elastic modulus and fracture mode CSG materials reinforced polypropylene fiber. Polypropylene fiber widely used for concrete reinforcement is randomly distributed into cemented sand. The two types of polypropylene fiber (monofillament and fibrillated fiber) were used and fiber fraction ratio was 0, 0.2 %, 0.4 %, 0.6 % and 0.8 % by the weight of total dry soil. The effect of fiber fraction ratio and fiber shape on compaction and compressive strength were investigated. The optimum moisture contents (OMC) of CSG material increased as fiber fraction increased and the dry density of CSG material decreased as fiber fraction. Also, the maximum increase in compressive strength was obtained at 0.4 % content of monofillament and fibrillated fiber. CSG material behaviour was controlled not only by fiber fraction but also fiber distribution, fiber shape and fiber type.

• Journal of Powder Materials
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• v.23 no.3
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• pp.213-220
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• 2016

In this study, bulk nickel-carbon nanotube (CNT) nanocomposites are synthesized by a novel method which includes a combination of ultrasonication, electrical explosion of wire in liquid and spark plasma sintering. The mechanical characteristics of the bulk Ni-CNT composites synthesized with CNT contents of 0.7, 1, 3 and 5 wt.% are investigated. X-ray diffraction, optical microscopy and field emission scanning electron microscopy techniques are used to observe the different phases, morphologies and structures of the composite powders as well as the sintered samples. The obtained results reveal that the as-synthesized composite exhibits substantial enhancement in the microhardness and values more than 140 HV are observed. However an empirical reinforcement limit of 3 wt.% is determined for the CNT content, beyond which, there is no significant improvement in the mechanical properties.

• Hwankyungkyoyuk
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• v.9 no.1
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• pp.90-99
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• 1996

This study focused on the investigation of objects and contents of environment-related chapters which were contained in the biology textbooks of middle school in the 5th curriculum, and in the 6th curriculum. As a result of objects analysis, cognitive domain such as the knowledge and information categories were allocated more than affective domain as skill, value and attitude, and behavior and participation. Compared with the 5th curriculum, the average-pages of environment-related chapters in the 6th curriculum were decreased. Environment-related chapters in the 6th curriculum also dealt negligibly with the real environmental problems in our country. Therefore the importance of the environment-related chapters of biology textbooks in the 6th curriculum was relatively deceased compared with that in the 5th curriculum. In considering the actual low optional rate of environment subject in middle school, it was thought that the reinforcing effect of environmental education can be hardly expected. Rather, the status of environment subject will grow weaker and weaker. Thus, in order to avoid the deterioration effect of its status and solve its problems, it is necessary to up-grade environment subject as obligatory course or needs strong reinforcement of environmental education.

• Korean Journal of Social Welfare
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• v.61 no.4
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• pp.217-241
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• 2009

This study was to examine the generative process, contents and normative practice of social workers practice knowledge and grope the suggestion for the reconstruction of social work knowledge. The authors approched with reflective narrative method, Data were collected from six social workers who have engaged in social work. As result, when they have confronted unaccountable phenomenon they generated knowledge through self - reflection and these confirmed, reproduced through normative practice. The researchers proposed the abduction resoning form for the knowledge development method in social work practice field, the reinforcement of human studies in social workers educational process, reconstruction of the network practice.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.461-464
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• 2008

This study investigated mechanical properties of the concrete using standard contents which was existent fibers in korea to apply the method for reducing crack of the non-reinforced concrete for the public space of an apartment with a fiber reinforcement. Results were summarized as following. The slump was slightly declined corresponding to the increase of the surface area and bridge effect of the fibers. For properties of the hardened concrete, the compressive strength was slighty reduced caused by the decrease of bonding strength between fiber and cement paste. The tensile strength was little increased according to bridge effect of the fibers, and the flexible strength and length change due to the drying shrinkage did not showed remarkable tendency.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.4
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• pp.374-383
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• 2013

Objectives: The major objective of this study is to review overall and in detail the Corporate Manslaughter and Corporate Homicide Act 2007 in the U.K.and the principal contents of this act. Methods: A variety of articles related to the background and circumstances under which the legistration was enacted and the details of this act were investigated and analyzed. Results: In enacting Corporate Manslaughter and Corporate Homicide Act 2007, legislators mainly took elements of legal culture into account and focused on seeking to broaden the law on corporate manslaughter. An indictable offence is considered to have been committed if the way in which an organization's activities are managed or organised causes a person's death and amounts to a gross breach of the relevant duty of care owed by the organization to the deceased. The way in which its activities are managed or organized by its senior management is a substantial element in the breach. Upon conviction, a corporation may be ordered to remedy any breach, publicize its failures, or be given an unlimited fine. Conclusions: The enactment background and details of Corporate Manslaughter and Corporate Homicide Act 2007 is understood accurately. On the basis of the findings, it is necessary to heighten effectiveness of punishment.for senior management or corporations that cause a person's death in Korea.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.153-156
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• 2005

Nondestructive sensing of electrospun PYDF web and multi-wall carbon nanotube (MWCNT)/epoxy composites were investigated using electro-micromechanical technique. Electrospinning is a technique used to produce micron to submicron diameter polymeric fibers. Electrospun PVDF web was also evaluated for the sensing properties by micromechanical test and by measurement electrical resistance. CNT composite was especially prepared for high volume contents, 50 vol% of reinforcement. Electrical contact resistivity on humidity sensing was a good indicator for monitoring as for multifunctional applications. Work of adhesion using contact angle measurement was studied to correlate acid-base surface energy between carbon fiber and CNF composites, and will study furher for interfacial adhesion force by micromechanical test.

• Computers and Concrete
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• v.21 no.1
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• pp.1-9
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• 2018

Electrical resistivity is a property associated with both the physical and chemical characteristics of concrete. It allows the evaluation of the greater or lesser difficulty with which aggressive substances penetrate the concrete's core before the dissolution of the passive film process and the consequent reinforcement's corrosion begin. This work addresses the steel fiber addition to concrete with two types and various contents from 0% to 1.3%, correlating it with its electrical resistivity. To that effect, 9 different mixes of steel fiber reinforced concrete (SFRC) were produced. The electrical resistivity was evaluated on the on six years aged SFRC by direct measurement at different frequency from 0.1 kHz to 100 kHz. The results indicate that steel fiber content is strongly conditioned by the type and quantity of the additions used. It was also found that long type of fibers has more effect on decreasing the electrical resistivity of concrete than short fibers. Therefore, they increase the corrosion risk of concrete depending on fiber volume fraction and moisture percentage.

• Journal of the Korea Furniture Society
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• v.24 no.4
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• pp.379-388
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• 2013

In this study, the effect of various glass fiber (GF) contents in a shell layer and shell thickness changes on the flexural property of coextruded wood plastic composites (WPCs) in combination with three core systems (weak, moderate, and strong) was investigated. GF behaved as an effective reinforcement for the whole coextruded WPCs and GF alignments in the shell layer played an important role in determining the flexural property of the coextruded WPCs. At a given shell thickness, the flexural property of the whole coextruded WPCs was improved with the increase of GF content in shell. For core quality, when the core is weak, increase of GF content in shell led to improved flexural property of the whole composites and increase of shell thickness helped it. On the other hand, when the core is strong, the flexural property of the whole composites showed reduced features at low GF content in shell and increase of shell thickness aggravated it. This approach provides a method for optimizing performance of the coextruded WPCs with various combinations of core-shell structure and properties.