• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.861-862
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• 2009

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.4
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• pp.339-347
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• 2006

Oral leukoplakia is the most common premalignant lesion and malignant transformation has been reported from verrucal lekoplakia. Homogenous, benign leukoplakia develops into a line of squamous cell carcinoma such as verrrucous carcinoma, papillary squamous cell carcinoma and invasive squamous cell carcinoma. Early diagnosis and intervention of premalignant leukoplakia is up-most important to prevent transformation into a oral squamous cell carcinoma. Any change in surface, size and color warrants repeated biopsy. If verrucous carcinoma is evidently derived from the previous leukoplakia, wide surgical excision and periodic follow up is needed. Surgically removed lesion of leukoplakia has the tendency to recur. Follow-up is very important to patient and clinician. Although many therapies have been reported to oral leukoplakia and verrucal carcinoma, accepted treatment principle is not exist so far. But surgical removal is recommended as the treatment of choice.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.367-375
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• 1990

A data structure representing 3-D objects was designed for the personal computer. It is very simple to be used in the personal computers which have small memory and low speed. A homogeneous transformation for developing 3-D objects was derived. Each developing procedure consists of five transformations : one translational-three rotational-one translational. Developing a solid is a creative work. So the results of developing vary with the order of surfaces to be developed. One method to reduce the length of seam was considered. The programs used in this study were written in Pascal and Assembly and a modeller that generates 3-D primitives was included. This program is an interactive dual-screen system. While all the menus in Korean are displayed at the monochrome monitor, the development figures with projective views are drawn at the color monitor. The program has wide applications for plate works.

• Applied Microscopy
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• v.45 no.2
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• pp.52-57
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• 2015

Bulk metallic glass (BMG) shows higth strength, high elastic limit, corrosion resistance and good wear resistance and soft magnetic properties and has been considering as a candidate for new structural materials. But they show limited macroscopic plasticity and lack of tensile ductility due to highly localized shear deformation, which should be solved for real structural application. In this paper researches on the enhancement of plasticity of BMG were reviewed briefly. Introducing heterogeneous structure in glass is effective to induce more shear transformation zones (STZs) active for multiple shear band initiation and also to block the propagating shear band. Several methods such as BMG alloy design for high Poisson's ratio, addition of alloying element having positive heat of mixing, pre-straining BMG and variety of BMG composites have been developed for homogenous distribution of locally weak region, where local strain can be initiated. Therefore enhancement of plasticity of BMG is normally accompanied with some penalty of strength loss.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.403-408
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• 2012

In this study, the homogenous Pd nanoparticles (Pd NPs) were first prepared with bayberry tannin (BT) as the stabilizers. Subsequently, the obtained bayberry tannin-stabilized Pd nanoparticles (BT-Pd) were immobilized onto ${\gamma}-Al_2O_3$ to prepare heterogeneous ${\gamma}-Al_2O_3$-BT-Pd catalysts. Fourier Transformation Infrared Spectrum (FTIR) and X-ray Photoelectron Spectroscopy (XPS) analyses confirmed that the Pd NPs were well stabilized by the phenolic hydroxyl groups of BT. Transmission Electron Microscopy (TEM) observation indicated that the diameter of the Pd NPs can be effectively controlled in the range of 4.2-16.0 nm by varying the amount of BT. It is found that the ${\gamma}-Al_2O_3$-BT-Pd catalysts exhibit highly activity for various olefin hydrogenations. For example, the initial TOF (turnover frequency) of the ${\gamma}-Al_2O_3$-BT-Pd in the allyl alcohol hydrogenation is as high as $12804 mol{\cdot}mol^{-1}{\cdot}h^{-1}$. Furthermore, the ${\gamma}-Al_2O_3$-BT-Pd can be reused 5 times without significant loss of activity, exhibiting a superior reusability as compared with conventionally prepared ${\gamma}-Al_2O_3$-Pd catalysts.

• The Journal of the Korea Contents Association
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• v.14 no.8
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• pp.40-49
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• 2014

Globalisation has intensified the international movement of labour and South Korea is no exception. Korea, which in the past was itself a labour-exporting country, has seen a reversal in human mobility since the late 1990's with a rapid growth in immigration and a transformation of a previously almost ethnically homogenous society. In this context, the important questions about the cultural and political implications associated with the construction of minority representations in the media have remained highly unexplored. The starting point of this study is an examination of the vital role of public service broadcasting (PSB) in Korean society, where ethnic minorities have increasingly become visible. The study shows the significant role of PSB in representing cultural diversity in public debates and the ways in which such representations and their dissemination reflect media power.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.199-199
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• 2011

The addition of a carbanion to ${\yen}{\acute{a}}{\yen}{\hat{a}}$-unsaturated carbonyl compounds is of importance in the C-C bond formation reactions for modern pharmaceuticals and organic synthesis. Recently, heterogeneous asymmetric catalysis became more attractive area of research because of the easy recovery and separation of the catalyst from the reaction system. Most of synthetic methods for heterogeneous catalysts were grafting or immobilization of homogeneous catalyst onto the solid supports. Trans-1,2-Diaminocyclohexane(DACH) and L-proline ligands have been enormously used as chiral ligands in several catalytic transformation under homogenous conditions. Our group prepared l-proline functionalized mesoporous silica was synthesized under acidic condition using a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer template (EO20PO70EO20, Pluronic P-123, BASF). Furthermore, we successfully directly synthesized trans-1,2 diaminocyclohexane functionalized mesoporous silica by using microwave method. The direct functionalization of chiral ligand into the framework of mesoporous materials is expected to be useful for the heterogeneous asymmetric catalysis. So, we adopt the direct synthesis of chiral ligand functionalized mesoporous silica by using thermal and microwave irradiation. Then, chiral ligand functionalized mesoporous silicas were applied to enantioselective asymmetric catalytic reactions.