• Journal of Biosystems Engineering
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• v.23 no.5
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• pp.417-426
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• 1998

This study was intended to investigate the characteristics of loads acting on the transmission of agricultural tractors during plowing, rotavating and transporting operations. A survey was conducted to determine working speeds and transmission gears most frequently used for each operations. The transmission loads were measured at the input shaft of the transmission gear box during each operations. Time histories of the measured torque loads were converted into a load spectrum and analyzed with respect to the S-N curve of the shaft material to estimate the partial damages on the transmission. Finally, comparison of the relative damages and severeness of each operation was presented and discussed.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.326-331
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• 2007

Large-scale molecular dynamics simulations are performed to verify the deformation characteristics of grain boundaries in nanolithography process. The copper substrate made of 200,000 atoms is constructed by two grains in different crystal orientations using dynamic relaxation method. The grain boundary is located in the middle of the substrate with $45\sim135$ degree angles. The plowing tip is made of diamond-like-carbon atoms in a variety of shapes. In the simulations, the generation, propagation, and accumulation of dislocations are observed inside the substrate. From the numerical results, we address the dynamic behavior of the grain boundaries as well as the frictional characteristics in terms of the morphology of initial grain boundaries.

• Tribology and Lubricants
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• v.14 no.4
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• pp.37-43
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• 1998

The friction loss between piston rings and cylinder liner is due to the tension of the piston rings. Lubricant is usually supplied to reduce the friction. However, the sliding speed of the piston varies during the reciprocating cycle and is very low near TDC(Top Dead Center)/BDC(Bottom Dead Center), where the hydrodynamic lubrication cannot be sustained. Since the lubrication regime is shifted from the hydrodynamic to the boundary lubrication near TDC/BDC, wear particles are easily generated so that the friction loss becomes bigger and bigger due to the plowing effect of wear particles. In this study, for the purpose of reducing the friction loss, an undulated surface is adopted to the cylinder liner to trap wear particles. The friction force variations, which are measured by strain gaged, show that the concept of undulated surface is one of the promising methods to effectively reduce the friction between piston rings and cylinder liner.

• Transactions of Materials Processing
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• v.13 no.1
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• pp.59-64
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• 2004

Nano-scratch tests were performed on PMMA thin films spin-coated on a Si substrate using an atomic force microscopy (AFM) with loads ranging form 10nN to 100nN. At low loads, a ridge pattern was formed on the PMMA thin film surface. No wear particles were observed during the pattern-forming mild wear. At high loads, severe wear by plowing occurred, accompanied by wear particles. The film with the highest hardness showed the highest wear resistance. Friction force generated during the scratching was measured, which was closely related with surface deformation of the film. A simple empirical equation to deduce scratch hardness of the film from a linear fixed-distance scratch test was proposed, and scratching-speed dependency of the scratch hardness was displayed.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.506-512
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• 2000

Performance of a four- wheel tractor fabricated by Tongyang Moolsan Co., Ltd, Korea was tested in Thailand during May-June 2000. Wheel slip and field capacity were measured in three fields using different traction devices and implements. The tractor worked satisfactorily in the test conditions. Wheel slip of 26.05-33.63 % and the field capacity of 0.17 - 0.20 ha/hr were observed during plowing operation. Further tractive performance tests using a three-point linkage configuration are recommended in Thailand field conditions. Different designs of cage wheels are recommended to be tested to optimize the tractive performance.

• Journal of Korean Society of Rural Planning
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• v.7 no.2 s.14
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• pp.3-11
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• 2001

A portable GPS receiver and a navigation software were used to investigate land application practices of manure composts. The field investigation indicated that most of the land application of manure composts were observed before April. Plowing for incorporation of manure with soil were continued from the middle of April. The results also revealed that over 60% of the farms were within 1 km from livestock farms from which manure composts were transported. Most of the farms having land application were dry field rather than paddies, Some of fields located near livestock farms frequently experience over-application of manure composts. It seems to have been difficult to complete the investigation in this study without the Gps/navigation system. The GPS/navigation system will become an essential tool in field investigations such as ecological/environmental monitoring works that require repeated observation at a number of sites.

• Journal of the Korean Society of Tobacco Science
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• v.15 no.1
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• pp.57-62
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• 1993

Ridger and vinyl mulcher for 8-10 PS power tiller which were distributed at the rate of one out of 2.3 farm households in Korea, was developed to ease the labor shortage of tobacco production. Devices wheel shaft extension by 30cm at both sides improved the stability of straight drive and enabled to save required labor hours by 50% for ridging at sloping field. Screw type blades were attached on center drive rotavator shaft, gear set was deviled to reverse the rotavator, and it was good at need to adjust the width and height for ridge. As the results, required labor hours for ridging and vinyl mulching could be saved by 90% as compared to conventional manual method after cattle plowing, and by 50% as compared to conventional power tiller method.

• Transactions of the Society of Information Storage Systems
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• v.2 no.3
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• pp.184-188
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• 2006

In recent years the flying height of the head/slider has been decreasing in order to increase the recording density of hard disk drive (HDD). Accordingly, it was predicted that direct contact between slider and disk surface (slider slap) can cause defects on the disk such as scratch and particle generation. In this work, we theoretically demonstrate the effect of rounded-edge slider using Hertzian contact theory. Depth and width of scratch were predicted by plowing model. Furthermore, as we fabricated rounded-edge slider, rounded-edge slider was tested and compared with sharp-edge slider. The experimental results show rounded-edge was effective for reducing scratch depth.

• Journal of the Korean housing association
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• v.21 no.4
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• pp.59-69
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• 2010

Imwongyeongjeji, Administration of Our Daily Life in Woods and Fields, is a sort of encyclopedia compiled by Seo, Yoo Goo in Joseon Dynasty in the 19th century. This voluminous work is made up of 16 chapters with various references including many articles dealing with architecture. The chapter Seomyongji covering the daily necessities contains a number of methods and materials of building construction. The distinctive feature of these articles is that they are mostly from Joseon's books. It is not similar to other chapters which are made of quotations from Chinese books. Especially, he quoted many of articles about architecture from his own work Geumhwagyeongdokgi, Record of Plowing and Reading in Geumhwa. In addition, He selected only empirical knowledge, put it in the book, and commented on it in his judgment. These articles provide valuable information on architectural knowledge in late Joseon period.

• Journal of Biosystems Engineering
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• v.32 no.4
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• pp.223-229
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• 2007

This study was conducted to develop a 2 row type band furrow tiller for a walking cultivator. The tillage and weeding operations in the furrow of dry fields has been done manually or chemical herbicide has been applied. The application of herbicide induces soil pollution and manual operation requires heavy labor. This 2-row type implement was developed to substitute this manual operation and to minimize soil pollution. The developed implement was composed of power transmitting device, tilling device, frame and tail wheel. The max. plowing width and depth were 300mm and 180mm, respectively. The revolutions of the hexagonal shaft and the tillage shaft were $227{\sim}376rpm$ and $355{\sim}590rpm$, respectively. The adequate working speed was $0.50{\sim}0.83m/s$ and the field capacity was $0.17{\sim}0.28hr/10a$.