• 한국세라믹학회지
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• 제22권2호
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• pp.11-16
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• 1985

The semiconducting ceramics having positive temperature coefficient of resistivity in he family of 0.25mol% $Sb_2O_3$ doped barium titanates were prepared with AST ($4Al_2O_3$.$9SiO_2$.$3TiO_2$) and $MnO_2$ as additives and these electrical properties were investigated. The PTCR characteristic in these ceramic materials was improved by the addition of AST and $MnO_2$ because the addition of AST decreased the room temperature resistivity and controlled grin size due to the formation of a liquid phase during sintering and the addition of $MnO_2$ improved by forming acceptor level on the intergranular layer. On dependence on the switching time as switching temperature was increased the initial power and switching time increased.

• 한국주거학회논문집
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• 제13권5호
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• pp.1-8
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• 2002

Contemporary architecture shows complex aspects of various design in form and material. Such trends even change classical materiality and this concept is believed to be the background of current ideas - digital, information, imagination with paradigm. This study inquires the general concept of dematerial. In the process searching for the forming basic background this study understands the characteristic. With characteristics drawn in chapter three, this study show the present status of the architectural expressions in the contemporary house in Korea under its dematerialized situation. And like this, we know fur study about the relation between dematerialization and current architecture, still more Korean present condition.

• 한국가구학회지
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• 제19권1호
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• pp.22-32
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• 2008

Revolution of software and hardware technology changed TV from cathode-ray tube to a LCD or PDP. And this change calls for change of TV decoration cabinet. The flat panel TV stands market is very a world-wide enormous size with the function which is various and breed and design is forming. Nonetheless, Our flat panel TV stands production method and technique is to a phase which imitates the product of the foreign nation which precedes. Currently our country TV / AV decoration cabinet is staying to only the acceptance function which is simple. Consequently, the development of the new flat panel TV stands that matches in the house culture which is modernized with applies the visual effect which is various, effective design and function is necessary. The fact that it develops the product which equips the function characteristic which is new and convenient is objective of sample planning.

• 한국자동차공학회논문집
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• 제10권3호
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• pp.159-165
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• 2002

So far, an alternator pulley has been formed by cold forging and casting with a metal due to the necessity of its high strength. Various advantages such as the light weight, the low cost, and the high productivity can be obtained by the injection molding process using engineering plastics. Engineering plastics have an excellent performance in the characteristics off strength vs. weight, a good forming ability and a productivity. The object of this study is to develop an alternator pulley, which has been made with a metal, using the injection molding process based on Taguchi methods. A sink mark is considered as a characteristic parameter to improve the quality. The FEM Simulation CAE tool, Moldflow, is used for the analysis of injection molding process.

• 한국정밀공학회지
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• 제23권10호
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• pp.44-51
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• 2006

According to global trend of the expanding need of high-quality automobiles, the usage of small precise worm consisting of gearing part for motors to actuate convenience modules has increased rapidly. Precision of those worms has very sensitive characteristic to motor performance and noise. Forming process has been generally used to manufacture worms because of its mass productivity. However, it has problems such as deformation due to residual stress and wear of dies. Planetary milling and side milling are among alternatives using cutting tools. To overcome those problems the two machining methods have some contrast features in the sense of tool numbers and cutting mechanism. In this paper, machinability of both methods was compared in terms of cutting force, precision and cycle time.

• 오토저널
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• 제14권3호
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• pp.109-114
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• 1992

The purpose of this study is to experimentally research the effects of polymer additives on turbulent transition of Couette flow between concentric cylinders when outer one is rotating and inner one is at rest; the diameter ratio being 0.2. Aqueous polymer solution generate the degradation phenomena in machine forming work, but this is not effected in about 10 minute at 5ppm. aqueous polymer solution testing. The Reynolds number, referred to the gap distance and rotation velocity of the outer cylinder, of turbulent transition is about 20000 for water flow. In the laminer region, the torque value is as same as theoretical one in the region of low Reynolds number, but becomes high with an increase in the Reynolds number. The polymer additives reduce the Reynolds number for turbulent transtition. In the turbulent region, the torque is remarkably reduced by the polymer additives, soluble polymer take down effect of turbulent transition boundary torque.

• 한국자동차공학회논문집
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• 제2권1호
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• pp.96-105
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• 1994

Cup drawing tests were performed to evaluate the friction characteristics of sheet metals. The linear relationship between drawing force and blank holding force obtained from the cup drawing test was used to calculate the coefficient of friction of the sheet metal. The friction coefficient was compared to that from conventional draw bead friction test. It was clarified that the cup drawing test can be used as a simple and convenient method for evaluating the friction characteristic of the sheet metal and also lubricity of the lubricant used.

• Journal of Microbiology and Biotechnology
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• 제11권2호
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• pp.193-198
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• 2001

Preparation of antibacterial biopolymer film which is suitable for food packaging film was investigated using K-carrageenan as a base material. K-Carrageenan showed good biodegradability and film-forming characteristic but poor mechanical properties under humid condition. Also, various bacteria grew well on its surface. The poor mechanical properties could be improved by mixing with alginate at a 1:1 ratio and crosslinking with $CaCl_2$ solution. Antibacterial property coul be provided by modifying the K-carrageenan film surface with acrylic acid plasma followed by ion-exchange with $Ag^+$ ions. Such prepared film still showed good biodegradability by various fongi.

• Journal of Korean Neurosurgical Society
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• 제40권5호
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• pp.373-376
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• 2006

An astroblastoma is a rare primary glial tumor occurring preferentially in young adults. It is characterized by a perivascular arrangement of the tumor cells forming perivascular pseudorosettes mimicking ependymomas. The histogenesis of astroblastoma is unclear, despite a number of studies to determine its possible cellular origin. We have experienced a case of astroblastoma located at the temporal lobe. It presented as a large, well-circumscribed, and highly enhanced mass lesion on magnetic resonance images[MRI]. The tumor was well demarcated and did not infiltrate the brain, which made complete removal possible. Here, we report and discuss the characteristic histological and radiological features of this case.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 춘계학술대회 논문집
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• pp.385-388
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• 2004

The influence of material properties and process parameters on the strain distribution of stamping parts was studied by finite element method. For the parametric study, the investigation of variation of material properties was carried out with tensile test for a dozens of different steel sheets. The friction test for each surface and lubricants conditions are also carried out because the frictional characteristic is important parameter fur sheet metal forming. The geometry of stamping parts was measured by 3D scanner to build the tool model fer the FE analysis. As a result of analysis the major process parameter fer each automotive parts was investigated.