• Transactions of Materials Processing
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• v.7 no.1
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• pp.66-71
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• 1998

The present study is concerned with the hydrostatic extrusion process of copper-clad aluminium bar to investigate the bonding conditions as well as the basic flow characteristics. Considering the bonding mechanism of bi-metal contact surface as cold pressure welding the normal pressure and the contact surface expansion are selected as process parameters governing the bonding conditions, in this study the critical normal pressure required for the local extrusion-the protrusion of virgin surfaces by the surface expansion at the interface-is obtained using a slip line method and is then used as a criteron for the bonding. A rigid plastic finite element method is used to analyze the steady state extrusion process. The interface profile of bi-metal rod is predicted by tracking the paths of two particles adja-process. The interface profile of bi-metal rod is predicted by tracking the paths of two particles adja-cent to interface surface. The contact surface area ration and the normal pressure along the interface are calculated and compared to the critical normal pressure to check bonding. It is found that the model predictions are generally in good agreement with the experimental observations. The compar-isons of the extrusion pressure and interface profile by the finite element with those by experi-ments are also given.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.3
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• pp.247-252
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• 2012

This study has been focused on application of ELID mirror-surface grinding technology for manufacturing single crystal optic sapphire. Single crystal sapphire is a superior material with optic properties of high performance as light transmission, thermal conductivity, hardness and so on. Mirror-surface machining technology is necessary to use sapphire as optic parts. The ELID grinding system has been set up for machining of the sapphire material. According to the ELID experimental results, it shows that the surface of sapphire can be eliminated by metal bonded wheel with micron abrasives and the surface roughness of 60nmRa can be gotten using grinding wheel of 2,000 mesh in 4.5um, depth of cut. In this study, the chemical experiments after ELID grinding also has been conducted to check chemical reaction between workpiece and grinding wheel on ELID grinding process. It shows that the chemical reaction has not happened as the results of the chemical experiments.

• Korean Journal of Breeding Science
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• v.49 no.3
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• pp.230-234
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• 2017

A mungbean variety 'Suhyeon' (Vigna radiata (L.) Wilczek) was derived from the cross between 'Jeonnam14' and 'IT208777' at the Jeollanamdo Agricultural Research and Extension Services (JARES) in 2010. 'Suhyeon' has erect growth habit, heart leaflet, green hypocotyl, black and straight pod when matured, and dull green seed surface. The stem length of 'Suhyeon' was 66 cm, which was 5 cm less than check variety 'Owool'. The pods number per plant of 'Suhyeon' was 24, which was 5 more than check variety. The sprout yield ratio of 'Suhyeon' was 8.67 times, which was 16% more than check variety. The contents of starch, protein and fatty acid of seed were 62.7, 27.3, 1.89%, respectively. The average yield of 'Suhyeon' was 1.74 ton/㏊, which increased 8% more than that of check variety. (Variety registration number: 5107)

• Journal of the Korean Wood Science and Technology
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• v.48 no.3
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• pp.345-363
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• 2020

This study was conducted to identify the effect of kerfing and incising pretreatments on high-temperature drying characteristics of cedar and larch boxed-heart timbers with a cross section of less than 150 mm. The result showed that the pretreatments have made a significant difference regarding surface check and shrinkage. Although the kerfing was suitable as a pretreatment to reduce the occurrence of surface check, the incising was not suitable as a pretreatment since the knives of timber joined together, causing the conversion to the surface checks. The shrinkage showed a significant result that the final moisture content was reduced in the order of incising, kerfing, and kerfing-incising after the drying process based on the pretreatment condition. Twist was more affected by the grain angle than the anisotropy of the juvenile wood, and there was no effect of pretreatments.

• International Journal of Highway Engineering
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• v.10 no.3
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• pp.189-197
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• 2008

Using a 5 year(2003 to 2007) pavement condition survey data from the highway pavement management system(HPMS), the roughness of the bridge deck pavement was analyzed. Based on the result of this analysis, this study tried to identify the factors affecting the deterioration of the bridge deck pavement condition. The data from HPMS indicates that the roughness of the bridge deck pavement is worse than that of the general pavement on the roadbed. The worse roughness of the bridge deck pavement is caused by the settlement of approach slab as well as the surface distress on the bridge deck pavement. In order to improve effectively the roughness of the bridge deck pavement, a management system was established in which not only the regular automated pavement condition survey to check the distress of surface of the bridge deck pavement was adopted but an automated surface profiler to check the degree of settlement of approach slab was applied.

• Korean Journal of Optics and Photonics
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• v.13 no.2
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• pp.166-170
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• 2002

Reflectors for reflective LCDs must be designed to be able to control the direction of the image and the viewing angle range for optimal display. In this paper, we tried to optimize the reflector for reflective LCDs. The conventional surface structures showed many defects and problems. Therefore we made efforts to improve the surface structures of the conventional reflectors through both a theoretical approach and analytic work. As a result, we proposed surface structures which showed almost uniform reflectance within the viewing angle range specified by a user even at any oblique incidence. By using Beckmann's equations, we could check the reflective property of the proposed surface structures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.7
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• pp.3197-3206
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• 2011

The objective of this study is to provide the guide for producing data for effective analysis of weapons systems and munitions. Therefore, the prototype from the study of creating the effectiveness data of surface to surface Artillery system under different battle environments was developed in this paper. For this purpose, mathmatical method which is in use of calculating Lethal Area and EFC(Expected Fractional Casualty) is analyzed and applied to the prototype for generating effectiveness data of surface to surface Artillery system. To validate the suggested prototype, we did the following actions: we select the source data corresponding to JMEM(Joint Munition Effectiveness Manuals) data and apply our prototype to the source data, and then match the results to check validity.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.4
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• pp.32-40
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• 1994

This paper describes a smooth surface interpolating method of ship hull using a three-dimensional currie net that comes from the mesh curve fairing process. Geometric continuity(($GC^1$) is preserved across the boundary curve between patches. The three-dimensional curve net can have nonrectangular topologies, such as triangular and pentagonal topology. Among the boundary curve interpolation methods, Hermite blended Coons patch, Convex combination, and Gregory patch interpolation method are used to generate the ship hull surface. To check the fairness of the surface, the numerical method of surface/surface intersection problem is adopted. An application to an actual ship hull is given as an example.

• Structural Engineering and Mechanics
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• v.70 no.4
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• pp.395-405
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• 2019

In the present work, the effects of cutting parameters on surface roughness parameters (Ra), tool wear parameters (VBmax), tool vibration (Vy) and material removal rate (MRR) during hard turning of AISI 4140 steel using coated carbide tool have been evaluated. The relationships between machining parameters and output variables were modeled using response surface methodology (RSM). Analysis of variance (ANOVA) was performed to quantify the effect of cutting parameters on the studied machining parameters and to check the adequacy of the mathematical model. Additionally, Multi-objective optimization based desirability function was performed to find optimal cutting parameters to minimize surface roughness, and maximize productivity. The experiments were planned as Box Behnken Design (BBD). The results show that feed rate influenced the surface roughness; the cutting speed influenced the tool wear; the feed rate influenced the tool vibration predominantly. According to the microscopic imagery, it was observed that adhesion and abrasion as the major wear mechanism.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.561-566
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• 2002

Recently, high quality exposed concrete is needed to achieve high quality surface for outer wall of the building. In this study, to solve above characteristic of the exposed concrete we selected self compacting concrete(SCC) and compared with normal concrete. So, we developed the SCC mix design and performed the semi mock-up test. Through this result, we performed the pilot test and mock-up test to check surface of outer wall and to measure formwork pressure As a result because SCC is better than normal concrete with respect to flowability and seggregation resistance SCC is suit to a exposed concrete needed high quality surface for outer wall of the building.