• Korean Journal of Environment and Ecology
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• v.16 no.3
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• pp.233-238
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• 2002

In this study, we investigated the lead exposure conditions using feathers of pigeons as a monitor for lead pollution from rural (Duckjeok Island), central urban (Seoul), and industrial complex areas (Yochon, Ansan, Ulsan, and Busan) in Korea. The feathers were taken from breast body parts and their lead analysis was performed without washing the feathers to reflect lead particles attached to the surface. The tissue lead concentrations were also compared with levels of atmospheric concentrations. The lead levels in the feathers were increased when the atmospheric lead levels were higher, so that the lead levels in the feathers of the pigeons from the industrial complex area with highest atmospheric lead levels were about four times greater than those of the rural areas. A positive correlation was found between the lead concentration of the pigeon's livers and feathers in rural, and the Yochon industrial complex area with the lowest lead levels. This result means that most of lead in feathers is transported from body tissues during the molting period without attached atmospheric lead. Thus, the feather lead concentrations could be discussed in the light of the metabolism known to occur between the liver and feathers. However, there were not significant correlations in the other areas with higher atmospheric lead levels, and observed relatively higher lead accumulation ratio in feathers than in livers compared with rural and the Yochon industrial complex areas. It is therefore suggested that the former was more exposure conditions and mainly influenced by outer pollutant sources than by the metabolism as the latter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.653-659
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• 2017

In this study, the complex forging process of an outer support ring was developed and the prototype was manufactured. The current process, hot forging and MCT machining, has a disadvantage of excessive material removal rates and longer machining hours. To overcome this disadvantage, a general shape is given through hot forging and the precision is achieved through cold forging. The complex forging process was developed with the minimal machining process. Forging analysis was carried out to design a forging process using the commercial program, Deform-3D. The hot and cold forging processes were set up based on the analyzed result. The mold and prototype were manufactured. Hardness, surface roughness, internal defect, the grain low line of the prototype were evaluated. The results showed no particular problems, and there were no problems in mass production. Using complex forging, the material was reduced by approximately 27 % compared to the process using hot forging and MCT machining. In addition, the production speed was improved 2.15 fold compared to that of hot forging and MCT machining. Through this study, a cost-effective process and mold design technology were established, which is expected to have positive effects on other related automotive parts production.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.131-134
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• 2007

A semi-solid forming technology has a lot of advantages compared to the die casting, squeeze casting and hot/cold forging, so semi-solid forming has been studied actively. Semi-solid forming has two methods. One is thixoforming with reheating of prepared billet, the other is rheoforming with cooled melt until semi-solid state. Thixoforging technology can produce non-dendritic alloys for semi-solid forming complex shaped parts in metal alloys. In this study, the thixoforging was experimented with made rheology materials by the spiral stirrer equipment. Rheology materials for forging were made by A356 casting aluminum alloy and A6061 wrought aluminum alloy. After experiment, forged samples were measured microstructure and were heat treated for high mechanical properties.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.226-229
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• 2008

Hot press forming is an advanced forming technology fur manufacturing of complex and crash-resistant automotive parts using ultra high strength steels. The 3-dimensional FE analysis of hot press forming process, in which process the deformation, heat transfer and phase transformation behavior are fully coupled, is carried out. The vast amount of material properties for the FE analysis is obtained from material properties calculation software which is based on thermodynamic calculations. The overall methodology for the FE analysis of HPF process and the analysis results are discussed here.

• Journal of Communications and Networks
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• v.1 no.3
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• pp.201-212
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• 1999

This paper studies the rapid design and implementation of the medium access control(MAC) and related interface circuits for 802.11 wireless LANs based on the field programmed gate ar-ray(FPGA) technology. Our design is thus aimed to support both the distributed coordination function (DCF) and the point coordination function(PCF) with the aid of FPGA technology. Further-more, in an infrastructure network, some stations may serve as the access points (APs) which may function like a learning bridge. This paper will also discuss how to design for such application. The hardware of the MAC and interface may at least consist of three major parts: wireless transmission and reception processes and in-terface, host(bus) interface, and the interface to the distributed system (optional). Through the increasing popularity of FPGA de-sign, this paper presents how Complex Programmable Logic De-vices(CPLD) can be utilized for speedy design of prototypes. It also demonstrates that there is much room for low-cost hardware prototype design to accelerate the processing speed of the MAC control function and for field testing.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.4
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• pp.93-98
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• 1999

Currently the technology of surface finishing is highly demanded in a wide range of industries. And many kinds of surface finishing technologies have been developed for each purpose. But it is still difficult to make a fine surface for the part which has three dimensional geometry. Now most of these kinds of complex parts are polished by hand by well skilled workers, This hand work process is inefficient and the production cost is high. Therefore it is desirable to develop a new finishing technology to solve problem In this study a new device was developed and tested in various test conditions.

• International Journal of Concrete Structures and Materials
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• v.2 no.1
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• pp.9-14
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• 2008

The cracking problem in concrete is widespread and complex. This paper reviews the problem and focuses on those parts of the problem that are more readily solved. Polymer fibers are shown to have promise in several important areas of the cracking problem. To investigate one of these areas of the cracking problem more completely, an experimental research program focusing on the early-age properties of fibers was carried out. This study researched the properties of four polymer fibers; two of the fibers were macrofibers, and two were microfibers. Each fiber was tested at several dosage rates to identify optimum dosage levels. Early-age shrinkage, long-term shrinkage, compressive strength, and tensile strength were investigated. Long-term shrinkage and strength impacts from the polymer fibers were minimal; however, the polymer fibers were shown to have a great impact on early-age shrinkage and a moderate impact on early-age strength.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.333-334
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• 2002

Injection-compression molding parts are many cases with complicated boundary condition which is difficult to analysis of mold characteristics precisely. In this study, the effects of various process parameters such as multi-point gate location, initial charge volume, injection time and pressure have been investigated using finite element method to fomulate the melt front advancement during the mold filling process. A general governing equation for tracking the filling process during injection-compression molding is applied to volume of fluid method. To verify the results of present analysis, they are compared with those of the other paper. The results show a strong effect of processing conditions as a result of variations in the three-dimensional complex geometry model.

• Fashion & Textile Research Journal
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• v.6 no.1
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• pp.9-16
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• 2004

The purpose of this study is to analyze expression of pluralism in contemporary fashion. This study has three parts. They are to understand the concept of pluralism, to find the fashion environments of pluralism in terms of politics, economics, sociality, culture, science, and art, and to analyze expression of pluralism in contemporary fashion. The concept of pluralism in contemporary fashion is the diversity and compounds of fashion images. The environments of pluralism in contemporary fashion are multinational economic system, virtual world of internet. mass-culture and postmodern art. And expression of pluralism in contemporary fashion is analyzed into publicity. Publicity is expressed by using things of common lifestyle and the past that people used to and are well-known. Horizontality is expressed by coordination of male-female facts and property-poorness without high or low concept. Multi-nation is expressed by mixing various kind of national characteristics and Virtuality is expressed by layering and collaging complex facts that are not connected each other.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.221-225
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• 2011

The railway system consists of many items such as sub-systems, equipments and parts to accomplish the required function. Also the railway system is very complex system that these items are connected with interface among items. According with this complexity, the process of system engineering is applied to the construction of new railway project to manage systematically. In addition, the research about system engineering is progressing in recent. The RAMS management is one part of system engineering, and is to assure the required safety and performance. Also, this RAMS should be managed through system life cycle. This paper show the case study of management of RAMS during construction and operation phase in respect of system life cycle. As a result of this research, the best way of RAMS management based on system engineering in operation phase for railway system is suggested.