• Bulletin of the Korean Mathematical Society
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• v.49 no.1
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• pp.213-222
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• 2012

We determine which K3 surface with Picard number 19 is a K3 cover of an Enriques surface.

• Korean Journal of Computational Design and Engineering
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• v.10 no.3
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• pp.162-167
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• 2005

A 3D solid element mesh generation algorithm was newly developed. 3D surface points of global rectangular coordinates were supplied by a 3D laser scanner. The algorithm is strait forward and simple but it generates hexahedral solid elements. Then, the surface rectangular elements were generated from the solid elements. The key of the algorithm is elimination of unnecessary elements and 3D boundary surface fitting using given 3D surface point data.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.249-250
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• 2002

In this paper, the relationship among the 3-D surface topography parameters are studied. Several surface topography parameters that are important in tribology are calculated against various surface topography data. 3-D surface data with desired properties are generated by using the non-causal 2-D auto-regressive (AR) model. The non-causal 2-D AR model is a random 3-D surface topography model that can generate 3-D surface topography data with specified parameters.

• East Asian mathematical journal
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• v.30 no.3
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• pp.321-326
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• 2014

In this paper, we present a simple proof of Corollary 3.3 in [5] using the fact that for a K3 surface of finite height over a field of odd characteristic, the height is a multiple of the non-symplectic order. Also we prove for a non-symplectic CM K3 surface defined over a number field the Frobenius invariant of the reduction over a finite field is determined by the congruence class of residue characteristic modulo the non-symplectic order of the K3 surface.

• Honam Mathematical Journal
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• v.38 no.1
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• pp.151-167
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• 2016

In Minkowskian 3-spacetime $L^3$ we find timelike or spacelike surface of revolution for the given Gauss curvature K = -1, 0, 1 and mean curvature H = 0. In fact, we set up the surface of revolution with the time axis for z-axis to be able to draw those surfaces on standard pictures in Minkowskian 3-spacetime $L^3$.

• Journal of Periodontal and Implant Science
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• v.34 no.4
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• pp.699-709
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• 2004

The present study was performed to evaluate histomorphological difference in various surface-treated implants in beagle. Implants($Implantium^{(R)}$, Dentium Co. Korea) with pure titanium machined surface, acid treated surface, and $Al_2O_3(50{\sim}100\;{\mu}m)$blasted with acid treated surface were used in this study. All mandibular premolars of $1.5{\sim}2$ year old male beagle dogs were extracted. At 3 months after extraction, the implants(${\Phi}$ 4mm, l 6mm) were installed. The beagle were sacrificed at 1, 3 months after installation and then tissues including implants were prepared for non-decalcified specimens. These specimens were analyzed comparatively under light microscope. The results of this study were as follow 1. Higher rate of osseointegration were showed in the $Al_2O_3(50{\sim}100\;{\mu}m)$blasted with acid-treated surface. 2. Increased osseointegration were showed in the $Al_2O_3(50{\sim}100\;{\mu}m)$blasted with acidtreated surface with time. 3. Higher maturation of integration were showed in the $Al_2O_3(50{\sim}100\;{\mu}m)$blasted with acid-treated surface. In conclusion, surface treatment of $Al_2O_3blasted$ with acid might be considered to shorten healing time and improve success rate as increasing contact of implant and bone.

• Journal of the Korean institute of surface engineering
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• v.51 no.1
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• pp.79-85
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• 2018

We systematically investigated the optical properties of sub-micron sized methylammonium lead tribromide ($CH_3NH_3PbBr_3$) cubes in the range of 100 to 700 nm, which were prepared by a surfactant-free precipitation method. We found that despite the strong absorbance, their photoluminescence quantum yield (PLQY) is very low as 0.009~0.011 % for whole range of sizes. Surfactant-free synthesis approach results in nanocubes that has no surface passivating reagents (e.g. surfactants) on their surface. As-prepared particles contain a large number of surface defects that may cause the low PLQY. The role of the surface defects were investigated in their photoluminescence decay process, which can be correlated with the particle size. Larger particles are characterized by a slower decay rate compared to smaller particles due to a large number of surface defects in the smaller particles that trap more excitons in the fluorescence decay process. These experimental results provide new insights into the fundamental relationship between surface state and optical properties.

• Journal of the Chungcheong Mathematical Society
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• v.27 no.2
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• pp.287-295
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• 2014

In this paper, we prove that the image of the representation of the automorphism group of a supersingular K3 surface of Artin-invariant 1 over odd characteristic p on the global two forms is a finite cyclic group of order p + 1. Using this result, we deduce, for such a K3 surface, there exists an automorphism which cannot be lifted over a field of characteristic 0.

• Journal of Technologic Dentistry
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• v.33 no.1
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• pp.47-54
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• 2011

Purpose: To investigate shear bonding strength between dental zirconia ceramics with different surface treatment and metal bracket. Methods: Zirconia ceramics(LAVA, 3M ESPE, USA) were divided to 4 groups according to their surface treatment; no surface treatment(G1), sand blasting(G2), silane coating(G3), and sand blasting+silane coating(G4). Specimens were bonded to metal bracket using resin bond($Transbond^{TM}XT$, 3M Unitek, USA). Shear bond strength was measured using universal test machine(3366 INSTRON. U.S.A) with cross head speed of 1 mm/min. Microstructural investigation for fracture surface was performed after shear test. Results: Shear bonding strengths of single surface treatment groups (G2 and G3) were higher than no treatment group(G1). Combined Treatment Group (G4) showed the highest shear bond strength of 9.15MPa. Microstructural observation shows that higher shear bonding strength was obtained when debonding was occurred at metal bracket/resin interface rather than zirconia ceramic/resin interface. Conclusion: Surface treatment of zirconia is necessary to obtain higher bonding strength. Combined treatment can be more effective when surface the surfaces are kept clean and homogeneous.

• Journal of the Korean institute of surface engineering
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• v.47 no.1
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• pp.25-32
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• 2014

The effects of shot peening pressure on electrochemical and surface morphological characteristics of ALBC3 alloy were investigated in this work. The surface hardness of ALBC3 alloy was improved by shot peening process under all shot peening pressures between 2 and 5 bar, and the hight value of surface hardness was observed to be about 420 Hv at 4 bar of the shot peening pressure. The shot peened surface presented very rough surface due to shot ball collision. The result of anodic potentiodynamic polarization in seawater revealed that there is no significant difference between the shot peened and non-shot peened specimen in terms of corrosion characteristics. Therefore, the optimum projection pressure is determined to be 4 bar.