• Journal of the Korean Mathematical Society
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• v.36 no.3
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• pp.447-458
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• 1999

In this paper we introduce a method of presenting 3-manifolds by polyhedral schemata with 2 vertices so that they may be naturally associated with given crystallizations of 3-manifolds. As applications, we explicitly present crystallizations of n-fold cyclic branched coverings of S over 2-bridge knots.

• Proceedings of the Materials Research Society of Korea Conference
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• 1995.11a
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• pp.34-34
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• 1995

• Communications of the Korean Mathematical Society
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• v.6 no.2
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• pp.299-310
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• 1991

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.4
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• pp.255-260
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• 1998

Behavior of solid phase crystallizations (SPC) of RF sputtered and LPCVD amorphous hydrogenated silicon film were investigated. LPCVD films showed the higher degree of crystallinity and larger grain size than sputtered films. The applicable degree of crystallinity was also obtained from sputtered films. The deposition method of amorphous silicon film influenced the behavior of post annealing SPC. Observed degree of crystallinity of sputtered films strongly depended on the partial pressure of hydrogen in deposition. The higher deposition temperature of sputtering provided the better crystallinity after SPC. Due to the high degree of poly-crystallinity, the retardation of larger grain growth was observed on sputtering film.

• East Asian mathematical journal
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• v.17 no.2
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• pp.239-251
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• 2001

We construct a family of 3-manifolds by pairwise identifications of faces in the boundary of certain polyhedral3-balls and prove that all these manifolds are cyclic branched coverings of the 3-sphere over the double link.

• Journal of the Korean Ceramic Society
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• v.19 no.2
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• pp.109-114
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• 1982

Fluoro-phlogopite crystals (Mica) were synthesized by two different methods; firstly the crystal was crystallized from the melts, and secondly mica crystalline was obtained from the direct solid state reaction. Addition of $CaF_2$ in the mica batch revealed the lowering the solid state reaction temperature. SEM and XRD were employed to observe mica crystalline flakes and solid solution forms. As a starting raw material Pyrophyllite was used resulting in the formation of mica crystals.

• Journal of the Korean institute of surface engineering
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• v.52 no.5
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• pp.275-281
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• 2019

Anodization is widely used to enhance the properties of aluminum, such as hardness, electric resistance, abrasion resistance, corrosion resistance etc. But these properties can be enhanced with additional process. According to the partial crystallization of oxide layer with post heat treatment, enhanced hardness can be expected with partial crystallization. In this study, post heat treatments were applied to the anodized aluminum alloys of Al6061 to achieve the partial crystallization, and crystallizations were evaluated with the reduced breakdown voltages. Interestingly, remarkable enhanced hardness (21~29%), abrasion resistance (26~62%), and reduced breakdown voltage (24~44%) were observed for the sulfuric acid anodized samples when we annealed the anodized samples with 1hour post heat treatment at $360^{\circ}C$. For the Al5052 alloys, a lot of cracks were observed when we applied the post heat treatment.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.5
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• pp.69-74
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• 2010

An increasing interest towards the investigations of chalcogenide glasses has been observed in the past years. This interest is due to their specific properties, as well as to the possibilities for their application in different fields of science. The optical devices, working on the basis of photoinduced phase transition between amorphous and crystalline state in the chalcogenide glasses, are a perspective for the micro- and nano-electronics. Here we were analysis basic physical properties for Ge-As-Se and As-Se chalcogenide glasses samples for characteristic for a planning of chalcogenide aspheric lens. From differential DTA/TG results, activation energies of the crystallizations of $Ge_{10}As_{40}Se_{50}$ and $As_{40}Se_{60}$ were approximately 3.6 eV and 3.3 eV, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.53-56
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• 1999

The weight decreases of the thermal deteriorated IV were rapidly increased at 80$0^{\circ}C$ and over. At the results of the analysis of the metallurgical microscope photographs. the surface of the thermal deteriorated IV at 30$0^{\circ}C$ was mixed with the elongated and original structures of Cu. But the elongated structures could not detected at 90$0^{\circ}C$ and over. The surface structures of SEM were detected a lot of small rounded particles between crystallizations. The EDX spectra of the thermal deteriorated IV at 3$0^{\circ}C$ were uniformly detected CuL, CuK, OK, and CIK, regardless of the scanning length, but the spectra of CIK could not found at 90$0^{\circ}C$. At the DTA curves, the endothermic reactions were occurred at about 25$0^{\circ}C$ to 30$0^{\circ}C$ and 43$0^{\circ}C$, and the exothermic reactions were occurred at about 48$0^{\circ}C$ respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.202-203
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• 2007

Ferroelectric SBT($SrBi_2Ta_2O_9$) thin films were deposited on Pt/Ti/$SiO_2$/Si substrate using R.F. magnetron sputtering method. The ferroelectric and electric characteristics were investigated with various post-annealing of Pt at $200{\sim}600^{\circ}C$. Compared with SBT thin film which had not post-annealed, the electrical properties and crystallizations of the SBT thin films were relatively improved by the post-annealing of Pt bottom electrode. The crystallization were characterized by X-ray diffraction (XRD). The electrical properties characteristics were observed by HP 4192A and precision LC.