• Journal of the Ergonomics Society of Korea
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• v.29 no.5
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• pp.751-762
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• 2010

The purpose of this study was to investigate the job stress factors of aircraft composite material part manufacturing workers using survey based on 'Job stress factors evaluation tool for Koreans' that was developed by KOSHA in 2003. Two hundred and fifty workers participated in this study, and among them 204 responses were analyzed for this study due to the unreliability and insincerity of responses. The eight job stress factors which are physical environment, job autonomy, job insecurity, organizational system, workplace culture, unfair compensation, relationship conflict, and job requirement were analyzed. The results showed that the stress level of the six job stress factors which are physical environment, job autonomy, job insecurity, organizational system, workplace culture, unfair compensation was relatively higher than that of other industry workers. Generally, all eight job stress factors showed higher stress with temporary workers than with permanent workers, and especially job autonomy, job insecurity, organizational system, and unfair compensation factors showed statistically significant differences (p<0.05). Since the temporary workers are insecure with their job, weak position in organization, having little self-control for the job and lower pay level than that of permanent workers though the job is as same as permanent workers', the stress level of above job stress factors would be much higher than that of the other factors. The group of unsatisfactory with workplace showed higher job stress than group of satisfactory with workplace in all job stress factors, as expected, at the statistically significance level (p<0.05). From the results of this study, the work loss due to the job stress could be prevented, and accurate stress factors could be removed at the workplace. Also the job stress management program can be implemented to improve the work efficiency and the workers' quality of life.

• Journal of the Korean Society of Clothing and Textiles
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• v.18 no.3
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• pp.368-386
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• 1994

The primary purpose of this study was to identify the diversity and embellishment of American Indian clothing and relationship between culture and clothing in American Indian Culture Areas. After the introduction of European material culture, change in American Indian clothing was conducted. The result of the Study as follows: 1. The most influential factors affecting the diversity of American Indian clothing were environmental factors. Climates and geographical features, Raw material were reflected in clothing style and clothing material in each culture Area. 2. Economic situation and life style were shown to be influential to clothing development. The best known instance of this was greatly elaborated clothing and personal adornment of the Plains who had higher stand of life and nomadic life style. 3. Religious concepts were important factors influencing American Indian clothing. Indian tribes had different ritual performance they used particular motifs in clothing. Clothing, such as "ghost shirt", Apache medicine shirt and Pueblo ceremonial clothing, served hidden pur- poses. 4. Techenology was another factor identified in this study as influencing American Indian clothing. Especially, weaving skills of Southwest played a great role in textile development. Pueblo "manta" and Navaho "bil" were famous for Indian costume. 5. European material culture allowed great change of traditional native Indian clothing. American Indian had new material, new styles, new concept of clothing. 6. American Indian, although Indian applicated European trade goods, was actually quite conservative in retaining traditional designs and modes of decoration. Asthetics and traction of American Indian were reflected in American Indian clothing.d in American Indian clothing.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1705-1712
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• 1994

Hilbert problems are derived to evaluate thermal stress intensity factors for a partially insulated crack subjected to vertically uniform heat flow in infinite bonded dissimilar materials. In case of fully insulated crack surface, the present solutions of thermal stress intensity factors are reduced into the same as the previous results. For the homogeneous material, mode II thermal stress intensity factor only exists. However, in the bonded dissimilar materials, both mode I and II thermal stress intensity factors are obtained. Specially, in this case, mode II thermal stress intensity factor is dominent. Also, thermal stress intensity factors are strongly influenced by the material properties. Thermal stress intensity factors decrease when the degree of insulation decreases.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.857-862
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• 2007

The purpose of this research is to compare the stiffness increment effects with the floor plan shapes by the stiffness increment factors. For this, we generated the standard floor plans with Box and T type shapes. Then applied the stiffness increment factors -outrigger, material strength, member section- to those floor plans, and generated several alternative analysis models that make the effects of the factors to the lateral displacement exposed. Finally, we analyzed the stiffness increment effects and compared with each other by the stiffness increment factors. As a result, we found that the increment effects have not influence to floor plan shapes, and orders of stiffness increment effects are outrigger, core wall and material strength. We expect that the results of this study could be effectively utilized in the schematic structural design of tall buildings.

• Journal of Korean Society of Water and Wastewater
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• v.16 no.6
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• pp.686-699
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• 2002

The purpose of this study is to estimate deterioration factors and weighting factors in pipe network which each local self-governments takes rehabilitation and replacement work present time. Deterioration factors in pipe network are able to effected of specific province or location related with water supply. Most of water supply pipes are laid under the ground, it is hard to quantify deterioration degree of water system. Moreover, the timing and economic limitation and insufficient information on the spot survey gives a difficulty to look over how old water supply system is. Accordingly, this study collects and analyses five data as the laying environment, visual analysis, analysis of soil contents, analysis of pipe material, and questionary survey data in water pipe of A city. The deterioration factor estimates 14 factors with excavation and experimental analysis and 9 factors without excavation and experimental analysis. Also, the weighting factors are estimated by using the multiple linear regressions and the linear programming. The estimated deterioration factor and weighting results are compared the analysis result of visual, pipe material, and soil contents with the Probabilistic Neural Network Model. Consequently, the model results of estimated 9 factors in this study and 14 factors show the 1-2% difference. The result show that the proposed model could be used to decide the deterioration condition of pipe line with real excavation and experimental analysis.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.16 no.4
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• pp.26-34
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• 2008

This article provides a comprehensive treatment of cracks in non-homogeneous structural materials such as functionally graded materials (FGMs). It is assumed that the material properties depend only on the coordinate perpendicular to the crack surfaces and vary continuously along the crack faces. By using laminated composite plate model to simulate the material non-homogeneity, we present an algorithm for solving the system based on Laplace transform and Fourier transform techniques. Unlike earlier studies that considered certain assumed property distributions and a single crack problem, the current investigation studies multiple crack problem in the FGMs with arbitrarily varying material properties. As a numerical illustration, transient thermal flow intensity factors for a metal-ceramic joint specimen with a functionally graded interlayer subjected to sudden heating on its boundary are presented. The results obtained demonstrate that the present model is an efficient tool in the fracture analysis of non-homogeneous material with properties varying in the thickness direction.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.1
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• pp.15-23
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• 2011

The purpose of this paper is to investigate the time behavior of a multiple crack problems. It is assumed that the medium contains cracks perpendicular to the crack surfaces, that the thermo-mechanical properties are continuous functions of the thickness coordinate. we use the laminated composite plate model to simulate the material non-homogeneity. By utilizing the Laplace transform and Fourier transform techniques, the multiple crack problems in the non-homogeneous medium is formulated. Singular integral equations are derived and solved to investigate the multiple crack problems. As a numerical illustration, transient thermal stress intensity factors(TSIFs) for a functionally graded material plate subjected to sudden heating on its boundary are provided. The variation in the TSIFs due to the change in material gradient and the crack position is studied.

• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.886-890
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• 2014

The properties of magnetic material of Nd-Fe-B are highly affected by various factors such as particle size, magnetic anisotropy, phase purity and crystal structure. Incorporation of excess neodymium was carried out in various percentages so that it will adjust the proportion of neodymium in the host crystal after reduction treatment and finally help to improve magnetic property of a material. The interdiffusion of Nd-Fe and boron was studied for various compositions and their effect on magnetic property was understood with theoretical concepts. The factors such as amount of hard and soft phase in the reduction treated product is also responsible for the possible exchange coupling between hard and soft phase magnets for better magnetic properties.

• Journal of the Korean Geotechnical Society
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• v.22 no.10
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• pp.33-45
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• 2006

C.S.G is a material made by adding cement and water to rock-like material such as riverbed gravel or excavation muck that can be obtained easily near dam si. Recently, the use of C.S.G is gradually increasing as the construction material for dam, road, revement and so on. Commonly, the strength characteristics of C.S.G is affected by various influence factors such as grade, unit cement, age and water contents. In this study, a series of compaction test and unconfined compressive strength test were performed to investigate the relationship between a strength and influence factors such as three kinds of gradation, age, unit cement and water contents with riverbed gravel in Hwa Buk dam. The results show that strength Properties of C.S.G is variously affected by these influence factors. Especially, gradation and water contents are found to be very important factors fur determining the strength of C.S.G material. And, from the results of experimental study, the correlation equations between uncompressive strength and these factors are proposed.

• Carbon letters
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• v.13 no.1
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• pp.23-28
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• 2012

Graphene is an attractive material for device applications, but device characteristics are very unstable because the graphene is very sensitive to environmental factors such as charges nearby the graphene, metal contacts, defects, contaminants and other adsorbates. Since the interactions between graphene and environmental factors affect the electrical characteristics of graphene devices, the interpretation of electrical characteristics as simple as current-voltage curves is non-trivial, despite the common practice of using well known electrical characterization methods that have been used in silicon MOSFET. This paper addresses major obstacles in the electrical characterization of graphene devices and offers countermeasures to improve the accuracy of electrical characterization methods.