• Journal of the Korean Society of Industry Convergence
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• v.7 no.4
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• pp.355-361
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• 2004

The finite element method were used to determine the stress intensity factor of cracked plate. The stress method, displacement method and J Integral are most popular finte element method. ANSYS proposed another a kind of displacement method. In this paper, it was examined that the accuracy and utility of the ANSYS method could believable to determine the stress intensity factors of centered inclined crack. Generally, inclined crack has two portion of stress intensity factors, tensile mode F1 and shear mode F2. For the purpose of increasing the accuracy of stress intensity factors, examined the effect of the numbers of nodes and elements, crack tip element size and number of partition of the crack tip vicinity. It was found that the method proposed by ANSYS is useful and has high accuracy. Accuracy of calculated stress intensity factors was increased by increase of the number of nodes and elements, and at the small size of crack tip elements can get more highly accuracy.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.3 no.1
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• pp.44-50
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• 1995

Abutment dies which resemble the actual size and shape of crown abutment is essential in most of the research area of fixed prosthodontics like marginal accuracy, crown seating, behavior of luting agent and so on. Seeing the large portion of research is done with round shaped dies in different size and cone angles, the necessity of research on the crown abutment is self-evident. 500 molar abutments were collected randomly through the commercial dental laboratoy, regrdless of their position in the dental arch, sex, and age. The measurements of 22 points of a die were done, and the results were as fogbows : 1. The height of the molar dies was $3.9{\pm}1.2mm$ 2. The bucco-lingual width was $8.9{\pm}1.2mm$ at the base, and $7.4{\pm}1.2mm$ at the occlusal. 3. The desio-sistal width was $8.2{\pm}1.2mm$ at the base, and $7.0{\pm}1.3mm$ at the occlusal.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.4
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• pp.53-58
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• 2003

Design of the corrugated watertight bulkhead for a bulk carrier is principally determined by the permissible limit of Classification requirements. As the weight of upper and lower stool has considerable portion of the total weight of the transverse bulkhead, optimum design including the stool geometry and size will play an important role on economic shipbuilding. The purpose of this study is focused on the minimization of steel weight using the design variables, which are the shape and the size of the corrugation as well as the upper and lower stools. Discrete variables are used as design variables for the practical design. In this study, the evolution strategies (ES), which can highly improve the possibility of leaching the global minimum point, are selected as an optimization method. Usefulness of this study is verified by comparison with the proven type ship design. As objective function, total weight of the transverse bulkhead including the upper and lower stools is used.

• Journal of the Korean Home Economics Association
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• v.29 no.2
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• pp.121-134
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• 1991

The farm housewive's labor has not been properly evaluated, although it has traditionally shared and devoted a substantial portion of the farm household economy. The objective of this study is to estimate the money value of rural women's labor. The data were got from the result of time analysis of farm housewives in 1988. Among the four estimation methods used in this study, the mixed approach of houskeeper replacement cost with individual function cost showed the greatest value in the decision criteria of different farming region, farming size, housewive's age, family size and children number. The opportunity cost approach showed the lowest value, however, is considered as the most appropriate estimation approach in rural situation in this study. It is expected that the appropriate estimation approach should be estimate the money value of rural housewive's labor and their economic position.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1347-1352
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• 2004

In this work, $TiO_{2}$ nanoparticles were synthesized using a $N_{2}-diluted$ hydrogen coflow diffusion flame. The effect of flame temperature on the crystalline structure and the size of formed nanoparticles was investigated. The maximum centerline temperature of the flame ranged from 1,920K for $H_{2}-only$ flame to 863K for 81% $N_{2}-diluted$ flame. When the temperature was higher than about 1,000K, the particle size was tend to increase due to the agglomeration and sintering among the primary particles. On the other hand, when the temperature was lower than 1,000K, the portion of anatase phase was greater than 80%.

• Journal of Biosystems Engineering
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• v.21 no.4
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• pp.474-481
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• 1996

Farm mechanization has been rapidly progressed in rice farming since the 1980's, in Korea. The mechanization has been achieved up to 95-97% in the year of 1995, except irrigation and drying process. However, rice production cost remains much more expensive than the cost of other rice farming countries. Since labor cost shares a major portion of the production costs, it is essential to save labor cost with automation and more sophisticated mechanization. However, it requires great capital investment which causes farm management worse. Therefore, the computer program was developed which can select machines to minimize the management and maintenance cost by analyzing available working days in different areas, machinery to purchase, farming size, total farming size in a village, number of machines and custom fee.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.3
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• pp.267-281
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• 2012

This paper reviews the flight mechanics and control of birds and bird-size aircraft. It is intended to fill a niche in the current survey literature which focuses primarily on the aerodynamics, flight dynamics and control of insect scale flight. We review the flight mechanics from first principles and summarize some recent results on the stability and control of birds and bird-scale aircraft. Birds spend a considerable portion of their flight in the gliding (i.e., non-flapping) phase. Therefore, we also review the stability and control of gliding flight, and particularly those aspects which are derived from the unique control features of birds.

• ALGAE
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• v.19 no.2
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• pp.149-151
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• 2004

Freshwater algae make up a very important portion of the autotrophic component of the aquatic food web. Therefore, the study of freshwater algal structure and biomass is central to aquatic ecosystem studies. Due to variations in cell shape and size for each species (or taxon) and survey site, cell abundance (or cell numbers per chosen volume) often leads to misrepresentation of the true importance of some species because of the great differences in size of various algae. Thus, it is necessary to investigate the freshwater algal species of a site in order to calculate the cell volume. Although direct cell counting, species volume measurement, as well as biomass calculation are time-consuming and requiring specialists in taxonomy.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.10
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• pp.1451-1457
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• 2002

When an aqueous liquid such as water having high electric conductivity and high surface tension is discharged from a nozzle under a strong DC electric field, fine drops ranging from 30 to 450 microns can be obtained only through the spindle mode. In the present study, effects of the electric conductivity and the surface wettability of nozzle materials on formation of drops with this mode were investigated. For that, three nozzles with the same size but with different materials were prepared and tested; a stainless steel needle, and a plain and a metal (gold)-coated (except for the tip portion) silica needles. Uniform drops were obtained with the gold-coated silica nozzle over the wider range of the DC voltage input. That is, formation of the liquid cone and detachment of the liquid spindle (ligament) can be more stabilized and frequent with the needles having high electric conductivity but with low surface wettability at their tips.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05a
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• pp.191-194
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• 2010

Construction companies are now trying a variety of cost-cutting strategies in the midst of recent slump of construction market. Notably, contract workers and local hires are accounting for increasing portion of management manpower as a part of their cost-reduction drive. However, construction site manpower researches to date have focused primarily on productivity analysis of site laborers, with little attention to the productivity of site management resources. This study aims to analyze the staffing status of office building construction site management manpower in reference to project size. Conclusions herein will provide basic inputs for subsequent attempts to build a model to enable efficient staffing of construction site management manpower.