• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.02a
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• pp.266-273
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• 2002

Milli-structure components are classified as a component group whose size is between macro and micro scales, that is, about less than 20mm and larger than 1mm. The bending of these components of thin sheets has a typical phenomenon of bulk deformation because of the forming size. The recent trend towards miniaturization causes an increased demand for parts with very small dimensions. The conceptual miniature bending process enables the production of such parts with high productivity and accuracy. The stress values of the flow curve decrease with miniaturization, which means that coarse grained materials show a higher resistance against deformation, when the grain size is in the range of the sheet thickness. In this paper, a new numerical approach is proposed to simulate intergranular milli-structure in forming by the finite element method. The grain element and grain boundary element are introduced to simulate the milli-structure of strip in the bending. The grain element is used to analyze the deformation of individual grain while the grain boundary element is for the investigation on the movement of the grain boundary. Also, the result of the finite element analysis is confirmed by a series of milli-sized forming experiments.

• Transactions of Materials Processing
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• v.8 no.3
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• pp.295-295
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• 1999

In the present study, the corrosion behavior of AZ91D as-cast alloy was investigated form the viewpoint of the distribution aspect of precipitate ($Mg_{17}Al_{12}$) and the variation of Al concentration in the Mg-rich matrix. The dendrite arm spacing (DAS) of an as-cast specimen was measured as a function of degree which describes the distribution aspect of the precipitate, and the salt spray test was conducted for various grain-sired specimens fur 20 days. The dendrite arm spacing increased as the grain size increased to about 150㎛, but a constant value is indicated when the grain size exceeds that range. Although the relationship between the corrosion rate and grain size is of a nonlinear type, the linear trend between the corrosion rate and the dendrite arm spacing is maintained for the overall range of dendrite arm spacing. Since the precipitate in the as-cast alloy is discontinuously distributed, this linear relationship means that the variation of Al-solute concentration in the Mg-rich matrix has a more potent effect than the protective action of the precipitate on the corrosion behavior of an as-cast alloy.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.34-42
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• 1999

In late 1997, the portion of registered light-duty diesel vehicle was 25.3% and its emission rate was 17.1% in Korea. Especially, diesel particulate matters(DPM) and NOx are hazardous air pollutants to human health and environment in urban area. The reduction technologies of exhaust emissions from diesel engines are improvement of engine combustion, fuel quality and development of diesel exhaust after treatment , In this study , a light-duty diesel oxidation catalyst(DOC) that is one of the diesel exhaust after treatment was made for performance evaluation and the emission characteristics were tested on CVS-75 mode. And the analysis of the particle size distribution with scanning mobility particle 100, 67.6% and 66.7, 10.0% for Pt and Pt-V catalyst .And for Pt catalyst, the PM increased 7.8% because of increasing sulfate but Pt-V catalyst reduced the PM to 23.0% . Test results of particle size distribution showed that peak values of number and mass densities are respectively 100∼200nm their distribution trend independent of vehicle speed.

• Macromolecular Research
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• v.15 no.7
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• pp.662-670
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• 2007

The crystallization behavior and fine structure of poly(ethylene terephthalate) (PET)/A-zeolite nanocomposites were assessed via differential scanning calorimetry (DSC) and time-resolved small-angle X-ray scattering (TR-SAXS). The Avrami exponent increased from 3.5 to approximately 4.5 with increasing A-zeolite contents, thereby indicating a change in crystal growth formation. The rate constant, k, evidenced an increasing trend with increases in A-zeolite contents. The SAXS data revealed morphological changes occurring during isothermal crystallization. As the zeolite content increased, the long period and amorphous region size also increased. It has been suggested that, since PET molecules passed through the zeolite pores, some of them are rejected into the amorphous region, thereby resulting in increased amorphous region size and increased long period, respectively. In addition, as PET chains piercing into A-zeolite pores cannot precipitate perfect crystal folding, imperfect crystals begin to melt at an earlier temperature, as was revealed by the SAXS profiles obtained during heating. However, the spherulite size was reduced with increasing nanofiller content, because impingement between adjacent spherulites in the nanocomposite occurs earlier than that of homo PET, due to the increase in nucleating sites.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2005.05a
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• pp.217-233
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• 2005

As the Kyoto Protocol will come into effect starting February 2005, 55 member countries of the Conference of Parties of the Framework Convention on Climate Change (FCCC) will be under obligation to reduce the emissions of Carbon Dioxide $(CO_2)$ by 5.2 Percent from the 1990 levels before the year 2012. Hence the development of technology to prepare for this has been accelerated in Korea. The effect of technology varies with market size of technology, and it is necessary to control technology development period, according to the size and trend of technology market. Moreover it is essential that market analysis be finished before technology development, because market on the $(CO_2)$ Reduction and Sequestration Technology expands internationally. For that reason, it is needed to analyze domestic market and to consider technology development strategy according to analysis results. In this paper, we analyzed the domestic industry and forecasted the market size, both related to the Reduction and Sequestration Technology on $(CO_2)$ emission, which is the major component of global Green House Gas(GHG).

• Journal of the Korean housing association
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• v.22 no.2
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• pp.121-129
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• 2011

The main objective of research is to present research outcomes in relation to the development of small size housings for 1 to 2 person households that have been increasing at a rapid pace due to many socio-economic factors. The method of this research was used by questionnaires. The effective numbers of survey questionnaire was 215, and the survey analysis has been made by using of SPSS win 12.0. The conclusions drawn from the research can be summarized as follows: 1) 1 to 2 person households can be typified by nine key characteristics according to the questionnaire designed to explore lifestyles and demands for new housing types. The nine lifestyles include information seeking urban dwellers, well-being oriented, practical trend followers, urban culture lovers, brand lovers, active listeners, easy life seekers, self-centered, and heavy consumers. 2) Occupants may need less space than they anticipate when more user-friendly and space conscious products and services are implemented. 3) There is a great potential market for small size housings if more convenient features and services are provided.

• Elastomers and Composites
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• v.44 no.3
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• pp.222-231
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• 2009

Shirasu-porous-glass (SPG) membrane emulsification is highly attractive in the field of toner industries, foods and drug delivery systems because of its easy control of particle size in micro-scale, narrow size distribution and multiple emulsion. The particle size and morphology of emulsion droplets can be controlled by changing the type of initiators, additives, monomers, crosslinkers and inhibitors in SPG membrane emulsification. In this paper, principles of SPG membrane emulsification, influence of process parameters and industrial applications have been addressed.

• Journal of the Korean Institute of Educational Facilities
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• v.9 no.3
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• pp.13-21
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• 2002

The new design concept for the middle school is developed as the seventh curriculum is published. However, the credible data for a plan study and spatial organization, and the type of rooms, and using area are hardly found. On this background, the purpose of this study is to provide fundamental resources for the design of middle schools and to recognize national status of plan organizations of middle schools with analizing the space and the type of rooms of collecting 150 schools' architectural plan drafted by city, province education office for 4 years(from 1997 to 2000) As a result, we know that although the class size of school is same, the area for school buildings is very diverse. Then, in order to increasing the area and to develop school buildings' quility, the meaning of standard level should be changed urgently minimum size to optimun size.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.11 no.1
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• pp.50-55
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• 1999

Gao and Collins method (two-dimensional sediment transport trend-vector model) using grain-size parameters (mean grain size, sorting coefficient, and skewness) calculated by the statistical moment method is introduced to understand semi-quantitatively the sandy and surficial sediment transport trends on a coast of the East Sea. The result is the sediment transport vectors which indicate transport paths of surficial sediment by wave-induced currents. The corresponding morphological feature is a spit developed at the mouth of the Nam¬dae stream, which is a resultant sediment transported by longshore current and is blocking the circulation of ocean. After this, it is thought that seasonal research and hydrodynamic measurements are needed for verification of the results.

• Journal of radiological science and technology
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• v.42 no.5
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• pp.357-363
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• 2019

To the basic information of patients with subarachnoid hemorrhage due to rupture of cerebral aneurysm treated with coil embolization, and to identify the general trend of treatment through classification according to hospitalization route, residence distribution, location and size of cerebral aneurysm, and procedure. A total of 164 patients with ruptured cerebral aneurysms treated with coil embolization were 54(32.9%) males and 110(67.1%) females. The sex and frequency of occurrence by age group were the most in 50s(31.3%), and among them, females were the most. The hospitalization route was the most common in 122(74.4%) people who were admitted to the emergency room through 119 evacuation, 79(48.2%) patients lived in where hospitals belong to the hospital. The season had 23(14%) in December, 18(11%) in January, 15(9.1%) in February, and the anterior circulation was 153(93%). The largest size was 5-7 mm found in 63(38.4%) patients. Patients underwent initial coil embolization for subarachnoid hemorrhage due to cerebral aneurysm rupture treated more patients than the incidence of the population. As a result of cerebral aneurysm rupture was seasonally affected, and winter occurs more frequently, female than male, age 50 is most common, and ruptured cerebral aneurysm is 5-7 mm in size.