• Journal of the Korean Society of Costume
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• v.50
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• pp.33-50
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• 2000

A comparative and an analysis of the resemblance and the particularity of the women's headgear which has been developed in accordance with each of climate and historical beck ground of the Eastern Slavs: the Russians the Belarusians and the Ukrainians those are deeply influenced by the culture of costume of the Scythians which is considered as the origin of the Koreans culture of costume is presented in this study. A well-known Russian ethnographer D. K. Jelenin classifies the women's head gear of the Eastern Slavs as a platok a chepetch a shapka and a unmarried women's venetch by its structural figure. Those 4 kinds of head gears are the basic head gears of the Eastern Slavic woman. However the characteristics and the features of the head gears of the Eastern Slavic woman However the characteristics and the features of the head gears of each nations show us that they have been developed differently not only by the climatic and the geological influences but also by the influence of their historical background. Furthermore we could realize that the Eastern Slavs had classified a person's social position and a standing in family members by the head gear. The incantational and the religious meanings of the hair styles and the head gears are shown in this paper. For instance they has been considered that a married woman without a hat is a disgrace and it even affects to the harvest. Even they believed that a corn styled Russian woman's hat named "Roga" protects a mother and her baby from the evil spirit. It seems that such a ethnographical culture is caused by their own faith of Russian orthodox and a non-Christian ancient religious culture of those regions.

• The Journal of Fisheries Business Administration
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• v.43 no.3
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• pp.43-57
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• 2012

According to the result of the recent survey on the current condition of loss of the fishing gears in the East, West and South seas, it is estimated that 50% of the fishing gears used for coastal trap and gill net fisheries are lost every year and 20~30% of those used for inshore trap and gill net fisheries are lost. It is reported that such loss of fishing gears leads to the loss of about 10% of 1.7M tons of the total annual catch from the gill nets and traps along the country's coasts and shores, which amounts to 15~170K tons. Submerged marine litters that have recently been accumulated because of the washed out or lost fishing gears significantly affect the development of fisheries resources as well as the natural environment. The purpose of this study is to identify the damages that the ever-increasing submerged marine litters of washed out fishing gears would have on the fishery and to analyze the effects of the coastal and inshore submerged marine litter collection business on the fishery management. For this, the economic analysis was carried out for the coastal and inshore submerged marine litter collection business based on the fishermen's expenses and earnings and their catch. The result of the analysis shows that the submerged marine litter collection business is quite effective in certain areas but rarely effective in other areas. However, taking into consideration that the litter collection would contribute to protecting the marine environment as well as the fisheries resources, it is expected to have a significant impact on the protection of the marine environment even in those areas where it is not effective for the protection of the fisheries resources.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.5
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• pp.1258-1265
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• 2016

The aim of this study was to evaluate the impact on the fishery resources and marine ecosystems by derelict fishing gears as part of the R & E (Research and Education) program that supervised by the busan metropolitan city office of education. In this study, we verified the ghost fishing effects caused by derelict fishing gears through the process which fish were caught to be attracted to bait for gillnet and trap in tank. In results, the dead fish to be gilled in gillnet and to enter in pot have been shown to attract other fish to the bait role. The result showed that the ghost fishing was caused by abandoned, lost or discarded fishing gears continuously. In particular, as a result of pot experiment, if the lost pot has a escape device, the entered fish could escape from the pot and the fisheries resources could protect from derelict fishing gears. In addition, the high school students are capable of raising the problem solving skills through carrying out the research project and expect to contribute to raising awareness about the protection of the marine environment.

• Journal of the Korean Society for Precision Engineering
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• v.1 no.3
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• pp.85-94
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• 1984

The WILDHABER-NOVIKOV gear, one of the circular arc gears, has the large contact area between the convex and concave profiled mating teeth, moves from one end of the tooth to the other axially making a face contact. Hence it provides a large load capacity than the Involute gear and still satisfying the law of gearing. In order to analyze the gear stress, a photoelastic investigation was carried out. Photo elastic model of the WILDHABER-NOVIKOV gears were made of Araldite CT200 in this investigation. For both the many teeth gear and the few teeth gear segments, External gears of all addendum type WILDHABER-NOVIKOV gear and the involute gear were tested. Included were the models with various profile raddi at the same pressure angle 20 .deg. and module 13.5. The flank stresses and fillet stresses of these gears were observed in each case and compared with those of gears. From this investigation, the following results were obtained. A. In the case of having many teeth gear: As the profile radius is increased, the fillet stresses of the WILDHABER-NOVIKOV gear become the same or less than that of the INVOLUTE gea, and the flank stress becomes smaller than that of the INVOLUTE gear. Therefore the better design condition is satisfied with a large profile radius. B. IN the case of having a few teeth gear: As the profile radius is increased the flank stress of WILDHABER-NOVIKOV gear becomes smaller than that of the INVOLUTE gear, but the fillet stresses become larger than that of the INVOLUTE gear. Therefore the larger design condition is satisfied with small profile radius.

• Tribology and Lubricants
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• v.35 no.1
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• pp.1-8
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• 2019

Demand for plastic gears are increasing in many industries due to their low production cost, light weight, applicability without lubricant, corrosion resistance and high resilience. Despite these benefits, utilizing plastic gears is limited due to their poor material properties. In this work, DLC coating was applied to improve the tribological properties of polyamide66 gear. 0 V, 40 V, and 70 V of negative bias voltages were selected as a deposition parameter in DC magnetron sputtering system. Pin-on-disk experiment was performed in order to investigate the wear characteristics of the gears. The results of the pin-on-disk experiment showed that DLC coated polyamide66 with 40 V of negative bias voltage had the lowest friction coefficient value (0.134) and DLC coated PA66 with 0 V of negative bias voltage showed the best wear resistance ($9.83{\times}10^{-10}mm^3/N{\cdot}mm$) among all the specimens. Based on these results, durability tests were conducted for DLC coated polyamide66 gears with 0 V of negative bias voltage. The tests showed that the temperature of the uncoated polyamide66 gear increased to about $37^{\circ}C$ while the DLC coated gear saturated at about $25^{\circ}C$. Also, the power transmission efficiency of the DLC coated gear increased by about 6% compared to those without coating. Weight loss of the polyamide66 gears were reduced by about 73%.

• Journal of Mechanical Science and Technology
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• v.14 no.1
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• pp.65-71
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• 2000

Mold cavities of gears should be made larger than the product specification since plastics shrink when changing from a molten to a solid state. For injection molded spur gears, two design methods for the compensation of shrinkage are widely used. One is the module correction method and the other is the pressure angle correction method. Both methods are based on the assumption that shrinkage occurs toward the center of a molded gear. This paper deals with the shrinkage rate and proposes a method of designing gear cavity derived from the measured shrinkage rates which govern the outside diameter, the tooth depth and the tooth thickness of a molded gear. The proposed method imposes no restriction on the shrinkage direction and provides a cavity with all of the fundamental gear design parameters.

• Tribology and Lubricants
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• v.1 no.1
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• pp.69-79
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• 1985

EHD(elastohydrodynamic) lubrication theories are applied to analyse the contact characteristies between the circular are profiled teeth of the plano-wheel gear and the cylindrical pin type teeth of the inner gear for the planocentric gears unit, For improving lubrication characteristic and contact frictional interference between the teeth, a new design method of optimising continuous meshing position is introduced, and the new tooth profile which is modified as a rounded curvature of the edge of circular arc is also suggested. The results of mathematical computation from conventional and the modified gear unit are compared, respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.2
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• pp.357-364
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• 2001

This study deals with the effect on non-martensitic layer on the fatigue strength in carburized gear. The test gears are carburized, then treated by the combination of chemical polishing and electro-polishing. Carburization treatment is used widely on parts of power transmission system like surface hardened layer to improve fatigue strength. Carburized gears are observed using a scanning electron microscope(SEM) to determine the characteristics of crack initiation mechanism in the surface layer. The constant street amplitude fatigue test is performed by using and electro-hydraulic servo-controlled pulsating tester. The S-N curves are obtained and illustrated. The effect of non-martensitic layer on the fatigue strength is clarified.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.3
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• pp.328-336
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• 1998

Marine reduction gears are usually used to increase the propulsion efficiency of propellers for ships powered by medium and small sized high speed diesel engines. Most of shaft systems adopt flexible couplings to absorb the transmitted vibratory torque from the engines to the reduction gears and to prevent the chattering phenomenon of reduction gears. However some elastic couplings show non-linear characteristics due to the variable torque transmitted from the main engines and the change of ambient temperature. In this study dynamic characteristics of flexible couplings sare investigated and their effects upon various vibratory conditions of propulsion systems are clarified. A calculation program of torsional vibration for the propulsion systems are clarified. A calculation program of Results of the program developed are compared with ones of the existing linear method and propulsion systems with the elastic couplings the transfer matrix method is adopted which is found to give satisfied results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.1
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• pp.92-99
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• 2003

Bevel gears are important mechanical parts to transmit power in transportation system high precision parts like bevel gears might be manufactured by closed die forging process for dimensional accuracy. Closed die forging of bevel gears offers the high quality and good mechanical properties and also leads to considerable cost saving. To determinate the proper closed-die forging process for bevel gear forms, three-dimensional finite element simulation for the progressive forging process was earned out and also the simulation results were compared with experimental results.