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선금주,Sun, Gum-Ju 대한치과기공학회 2011 대한치과기공학회지 Vol.33 No.4
Purpose: The purpose of this study was to know the availability of three photosensitizers, CQ, PD, DA, as a photosensitizer of dental resin composite. We want to know abortion band around visible light region for the using potential possibility as a photosensitizer for visible light cured dental composite resin. And I studied to know the relative photodecomposition ratio of three photosensitizers with or without photoinitiator, DAEM. Methods: The photodecomposition of three photosensitizers were studied by UV absorption spectroscopy in ethanol and determined by same instrument with irradiation time for relative photodecomposition. In order to study the effect of amine on photodecomposition was added the DAEM in the photosensitizer solution and the relative rate was measured by the same procedure with aove mentioned. Results: The all of three photosensitizers are absorbed around visible light region. The relative rate of decrease in absorbance incereased in the order: CQ < BD < PD. The effect of DAEM on the photodecomposition of the photosensitizers was appeared different results without DAEM. The photodecomposition rate of PD and DA decreased somewhat with the addition of amine, while that of CQ increased. The rtealtive photodecomposition rate increased in the oprder: BD ${\leq}$ CQ < PD with the addition of amine, but the differnce was not significant. Conclusion: PD and DA like CQ gives to the possibility of use as a photosensitizer for visible light cured dental composite resin by absorption around visible light region and photodecomposition in the maximum absorption wavelength. And it is showed that PD and DA are not effective decomposed with amine initiator, DAEM but CQ decomposed with DAEM effectively. This result may be due to a different mechanism operating for the decomposition of photosensitizers in the presence of amine.
전자론에 의한 생체용 Ti-Zr-Nb-Pd계 합금의 내식성 평가
정종현,선금주,Jung, Jong-Hyun,Sun, Gum-Ju 대한치과기공학회 2004 대한치과기공학회지 Vol.26 No.1
In order to understand alloying effects on the corrosion resistance of Ti-(10$\sim$20)%Zr-(2$\sim$8%)Nb-0.2%Pd alloys, Polarization curves were measured at 5%HCI solution. The results were interpreted in terms of two parameters obtained by the molecular orbital calculation ; one is the bond order($B_{\circ}$) and the other is the metal d-orbital level($M_{d}$). $B_{\circ}$ is a measure of the strength of covalent bonds between titanium and alloying elements. $M_{d}$ is correlative with the electronegativity of elements. It was found that increasing of Zr and Nb with higher $B_{\circ}$ values showed a lower critical anodic current density in the polarization curve and hence higher corrosion resistance. On the other hand, increasing of Zr and Nb with higher $M_{d}$ values showed a higher corrosion resistance.
치과용 가시광선 중합형 복합수지의 새로운 광개시제에 관한 연구
최용석,선금주,Choi, Yong-Seok,Sun, Gum-Ju 대한치과기공학회 2002 대한치과기공학회지 Vol.23 No.2
The photopolymerization efficiency and surface hardness of composite resin containing 1,2-phenylpropanedione (PD) and diacetyl (DA) as photoinitiators were studied by IR and Vickers hardness and the results were compared with that of camphorquinone (CQ). Relative photopolymerization efficiency of the photoinitiators increased in the order of DA < CQ < PD. Vickers hardness of composite resin containing the photoinitiators increased in the order of CQ < PD < DA. Thus, PD is a new visible light photoinitiator for dental composite resin with higher photopolymerization efficiency and surface hardness than that of CQ. Mechanical properties such as Vickers hardness, diametral tensile strength, and flexural strength of the experimental resin composite prepared by addition of the photosensitizer into a resin of bis-GMA improved with increasing the photosensitizer content and irradiation time. The resin composite of bis-GMA containing DA or PD shows better mechanical properties than that of CQ.
시클로부탄고리를 가진 감광성 poly(amide-imide)의 합성 및 특성
선금주 광주보건대학 2004 論文集 Vol.29 No.-
Photosensitive poly(amide-imide)s (PAIs) containing cyclobutane group were synthesized and studied for the properties of positive type photoresist. PAIs were prepared by direct polycondensation of N-(4-caboxyphenyl)maleimide cyclobutane dimer(p-MCD), N-(3-carboxyphenyl)maleimide cyclobutane dimer(m-MCD) and diamine with triphenylphosphite(TPP) and pyridine as a polymerization catalyst. The PAIs were insoluble in gerneral organic solvents, but fairly soluble in polar aprotic solvents such as NMP, DMSO, DMAc, DMF. Intrinsic viscosity of PAIs measured in NHP was 0.39 g/dL, 0.26g/dL. The onset of themal decomposition temperature was 426℃ which shows relatively high thermal stability. The PAIs were insoluble in THF before irradiation. However, they became soluble upon irradiation with 254㎚ UV light. This result shows that PAIs have the properties of positive type photoresists. Differnce FT-IR spectral study showed the photooxidation of amide and imide groups as well as photosplitting of cyclobutane rings took place during the photolysis of PAIs.
친수성기를 제거한 새로운 광중합형 복합수지 단량체의 합성과 수분흡수율에 관한 연구
선금주 광주보건대학 1993 論文集 Vol.18 No.-
2,2-Bis[4-(2-hydroxy-3-methacryloxy propyl)phenyl]propane(Bis-GMA) as a monomer of visible light cured dental composite resin was prepared and Bis-acetylated GMA was synthesized by acetylating the hydroxyl group of Bis-GMA for elimainating the hydrophilicity. Synthesized monomer were identified by fourier transform infrared spectroscopy(FT-IR) and fourier transform nuclear magnetic resonance(FT-NMR). Visible light-cured dental composite resrin were prepared from synthesized monomer and then compared water absorption with Silux^R, ready-made composite resin. Resin was prepared from Bis-acetylated GMA had lowest water absorption about 0.27% for a day and no more absorbed water.
선금주 광주보건대학 2003 論文集 Vol.28 No.-
A linear epoxide-amino type of a new polymeric HALS was prepared by an addition polymerization of 2,2-bis(4-glycidyloxyphenyl)propane(DGEBA) and 4-amino-2,2,6,6-tetramethylpiperidine (ATMP) in chlorobenzene. Two types of addition polymers, high molecular weigh tHALS (HMH) and low molecular weight HALS (LMH) were isolated by precipitation in acetone. The structure of HMH was characterized from the NMR and MALDI-TOF spectra. The effects of the reaction conditions on yield of HMH and LMH were observed by varying the reaction conditions such as monomer concentration, reaction temperature, and reaction time. The yield of HMH increased with the amount of the ATMP concentration, reaction temperature, and reaction time. HMH is fairly miscible with polystyrene (PS). The photostabilizing effect of HMH on the photooxidation of PS at 254 or 310 ㎚ was studied from the IR absorption spectral changes. The results indicate that the photostabilization effect of HMH was similar to or better than that of Cyabsorb UV-3529??, a commercially available polymeric HALS