• Journal of Welding and Joining
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• v.21 no.5
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• pp.513-517
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• 2003

Resistance welding processes are widely used in automotive applications. In particular, Mash-Seam resistance welding is typically used in Tailored Blank process. If spot welds are changed to a continuous weld, it's easy to reduce noise and to be more stable in cars. A arc welding, laser welding, seam welding using wheel electrode are available to make continuous welds on a car body, but they demand operator with advanced skills and expensive cost to develop. Therefore, flat electrode continuous mash-seam resistance welding process has been used to improve the weak points in currently available system in lap seam welding. This developed process has much more strength and air tightability, and also has much better plastic workability than laser welding. Moreover, commercial RSW machine can be readily used in this welding process.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.57-64
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• 1996

Lately, rapid expansion of construction industry and following increment of demand for concrete in the construction created shortage of aggregates in the nation. Supplement of good quality aggregate is an immediate issue for the construction industry to solve. Therefore, this study evaluated a possibility of using coal mine waste collceted from Kwangwon-do region as a source of aggregate in manufacturing polymer concretes which have high strength and high durability. First, aggregates were obtained by crushing coal mine waste and polymer concrete was manufactured using these aggregate. Mechanical property test results for the polymer concrete showed that the coal mine waste aggregates were acceptable to use as a replacement of the aggregate in polymer concrete manufacture.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.349-354
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• 2003

The objective of this paper is to investigate the length change of high performance concrete using expansive additives to reduce autogenous shrinkage and drying shrinkage. The kinds and the contents of expansive additives are varied. The expansive additives are used made from Japan(CSA type;JEA), China(CSA type;CEA) and Korea(gypsum type; KEA), respectively. According to results, remarkable variations of the properties at fresh concrete are not found with dosage of expansive additives. For compressive strength, it decreases about 6-10% with expansive additives of 10%. Autogenous shrinkage decreases about 32%, and drying shrinkage does about 35%, respectively, with expansive additives of 5%, and about 68% and about 55%, with expansive additives of 10%. Accordingly, expansive additives demand requires 10% by cement weight in order to reduce shrinkage of high performance concrete more effectively in the sphere of this study, and JEA shows the best shrinkage reducing performance among the tested expansive additives.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.257-260
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• 2006

West coast of Korea belongs to the five largest tidal-flat zones in the world. Aiming at the efficient management and preservation of the eco-system and the enhancement of the bio-productivity of the tidal-flat zones, development of a environment-friendly vehicle for tidal-flat area is being attempted. This paper deals with the description of the characteristics of the tidal-flat zones of west coast of Korea, the technology assessment of the related products in the ATV(All-Terrain Vehicle) market, the demand assessment for the resident people.

• Journal of the Korea Institute of Building Construction
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• v.5 no.2 s.16
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• pp.131-138
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• 2005

Most concrete is recently made of an aggregate which is properly absorbed, and carried in it in order to do capability at every fields. We have been close to demand new rapability of high flowing and enduring for specific concretes. That is difficult to cope with claiming the efficiency on deterioration from lack of a high quality aggregate. Therefore, For solving the problems we apply to a packing method for using dried materials. That is to say that it is a kind of making into an instant. In this study. There is a purpose to present fundamental data, comparing and analyzing a phenomenon of aggregate's absorption following the rate of adding water, for using existing materials.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.424-429
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• 2003

Hot gas path components, which are made of nickel based superalloys, are subject to periodic replacement due to degradation of thermomechanical properties that might bring catastrophic failure during normal operation of gas turbine units. In order to rejuvenate the metallurgical condition of the serviced components, heat treating techniques such as solution annealing and aging heat treatments have widely been employed. However, the effectiveness of those typical heat treatments is not apparent enough in terms of quantitative grounds. On the other hand the demand of the rejuvenation heat treatment and hot isostatic pressing (HIP) have constantly been raised by the end users. Therefore it is necessary to verify how the typical heat treating techniques affect to the aged and degraded material. As the result of experimental work in this study, GTD-111 and GTD-222 Ni-based superalloys were collected and analyzed quantitatively through microscopic observation, microhardness evaluation and creep test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.5
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• pp.601-608
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• 2007

To meet demand of big capacity and high speed rotation for washing machine, more stress from bending and twisting are complexly loaded onto the shaft supporting the horizontal drum, causing problems in fracture strength and fatigue life. Shafting system is mainly divided into flange and shaft. Flange is located between the drum and shaft, transferring power from the shaft to drum, and acting as a supporter of the back of the drum. Because section of flange has various design factors according to configuration of flange, the optimum conditions can’t be easily determined. Using a design of experiment (DOE), this study was performed investigating the interaction effect between factors as well as the main effect of the each design factor under bending and twist and proposed optimum condition using center composition method among response surface derived from regression equation of simulation-based DOE.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.3
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• pp.113-120
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• 2010

Reduction factor for installation damage required to calculate design strength of geogrid used in MSEW(mechanically stabilized earth wall) design is usually obtained in the field test simulating real construction condition. However, damages occurred in geogrid during backfill work are influenced by many factors such as polymer types, unit weight per area, backfill construction method and gradation of backfill material and field test considering these factors demand lots of time and costs. In this study, factors affecting installation damage are analyzed and empirical method to evaluate reduction factor for installation damage using maximum particle size in backfill material is suggested.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.141-143
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• 2007

Increasing demand of using low weight materials in recent automotive trends has been the challenge to develop a sound welding of aluminum alloys. A heat treatable AA6082-T6 and a non-heat treatable AA5083-0 aluminum alloys were joined in this study. Investigations revealed that about 60 UTS will be reduced due to welding process. Fracture happened in the interface between fusion zone and base metal of top specimen where penetration is shallow. Therefore, lower welding torch angle produced the better strength which allows deeper penetration to the top specimen. PWHT at $560^{\circ}C$ for 2 hours can be used to return the original UTS of the specimens.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.129-136
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• 2005

The demand on thermos furnace of Al molten metal has recently been getting higher and higher according to the increase in use of Al and Al alloys. This study considers the estimation of the thermal and mechanical stability in the thermos furnace for Al casting. It is executed through the analysis of heat transfer on the refractory material and heat stress on each steel shell. Also, the estimation of structural stability was appraised through the strength analysis of the lower structure. In result, the temperature of steel shell rose to 320.15K and its elastic deformation was about 1.5mm. The elastic deformation of the lower structure was about 0.66mm. As a result of it, the data obtain from the analysis in this study are regarded as stable value on considering that the size of the furnace is 2500mm.