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가시광선중합화에 따른 충전용 Glass lonomer Cement의 물리적 성질에 관한 연구
권혁춘,신동훈 大韓齒科保存學會 1992 Restorative Dentistry & Endodontics Vol.17 No.2
The aim of this study was to investigate the physical properties of visible light curing Glass Ionomer cement for restorative esthetic filling. The control group was the autopolymerizing GC fuji Glass Ionomer cement(2.2:1 P/L ratio) and the experimental groups were made by following procedure. To induce the polymerization by visible light, the powder of GC Fuji II GI cement and the liquid of vitrabond for base & liner were mixed in an amalgam capsule with 2.5:1, 3.0:1, 3.5:1 P/L ratio(% wt/wt). After fabrication of specimens, compressive strenght, fracture toughness (K_IC), Scanning Electron Microscope and X-ray Diffraction, water-leachable content, marginal leakage and surface roughness were studied. The results were as follows : 1. Only experimental No. 1 group(visible Light curing) showed less compressive strength than control group I hour after curing. strength was increased with aging in all groups, so the compressive strength of light curing groups was no less than that of autopolymerizing group after 3 weeks. 2. Experimental No.3 group(visible Light curing) was inferior to No. 2 group(visible Light curing) in fracture resistance but light curing groups were more resistant to fracture than autopolymerizing group and showed ductile fracture pattern as compared with the brittle fracture pattern of autopolymerizing group. 3. From scanning electron microscopic image, various sized unreacted powder particles, surrounded by silica gel, were embedded in polysalt matrix. Light curing groups showed little crack and more dense unreacted particles than autopolymerizing group. 4. From X-ray diffraction analysis, GC Fuji II Glass Ionomer cement powder and all groups showed glassy appearance but light curing groups seemed to be more intensive in crystaline than autopolymerizing. 5. The most significant dissolution was shown in early setting period in all group. Light curing groups were dissolved less than autopolymerizing group. 6. Marginal leakage was not different significantly in case of cavity margin composed of same tooth structure(ex. only enamel margin, only dentin margin) but much more leakage was shown in dentin/cementum margin than enamel margin. In only case of only enamel margin, light curing groups were superior to autopolymerizing group. 7. All groups showed relatively smooth surface, which inegularity was less than l μm. Light curing groups were smoother than autopolymerizing group.
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Iridoid 화합물이 치수절단 후 잔존치수 조직에 미치는 영향
권혁춘,박동성,손호현 大韓齒科保存學會 1997 Restorative Dentistry & Endodontics Vol.22 No.2
Aucubin, an iridoid glucoside, which is isolated form Aucuba japonica, has some biological effects. This study was to investigate the effect of aucubin on the remainig pulp tissues after pulpotomy. Mongrel dog's coronal pulps were mechanically exposed with a sterile round bur and excised with sterile sharp excarvator. After bleeding was controlled, in control group, Ca(OH)_2 powder was applied on the remaining pulps and the cavities were sealed with Z.O.E cement. In experimental group 1, mixed powder with Ca(OH)_2 and aucubin(1:1 by weight) was applied on the pulotomized pulp surfaces. After th cavities were covered with sterile aluminum foil, they were sealed with Z.O.E. cement. In experimental group 2, only aucubin powder was applied on the remaining pulps and then they were treated the same as experimental group 1. In the all groups, the pulps were histopathologically observed by light microscope at the time intervals of 1, 2 and 4 weeks after experiment. The results were as follows: 1. In control and experimental groups, mild vascular congestion and bleeding were found in most of the specimens. Less inflammatory infiltration was observed in experimental groups than in control group. 2. Dentin bridge formation was found after 1 week at both control and experimental group 1. Dentin birdge had discontinuous osteodentin like appearance of contained some dentin chips. In experimental group 2, dentin bridge was not seen. 3. The coagulation necrosis layer on the remaining pulp tissues was seen in all groups. In experimental group 2, the thickest layer was observed. And in control group, coagulation necrosis layer was similar as in experimental group 1.
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치근면에 항균 varnish 처치 전후의 치태 세균 및 치은열구액내 항체수준 변화에 관한 연구
권혁춘,도정욱 大韓齒科保存學會 1993 Restorative Dentistry & Endodontics Vol.18 No.2
In the prevention of root surface caries, antimicrobial therapy for the control of subgingival and supragingival plaque is seriously considered as a long term suppression of pathogenic microflora. Recently, varnishes containing antimicrobial agents have been developed to control the supragingival mocroflora. The purpose of this study was to determine the antimicrobial effects of 20% chlorhexidine varnish and 2.6% silane fouoride varnish with sealant. In clinical experiments, 12 subjects were selected from the periodontally treated patient and divided into 3 groups. after a dental prophylaxis, the subjects were treated with single application of placebo varnish(group 1), 20% cholrhexidine varnish(group II), and 2.6% silane fluoride varnish(group III). Root surface plaque samples were taken before(baseline)and one, two, four, and 8 weeks after the treatments. Microbiological examinations of root surface plaque were performed with culture study and indirect immunoflorescence(I.I.F) study, and immunological examination of gingival crevicular fluid antibody titers was performed with ELISA study. The results were as follows : 1. Pathogenic microflora on the root surface including S. murans, S. sanguis, s. mitis, A. naeslundii, A. viscosus were 24-37% on I.I.F. study. 2. S. mutans, S. sanguis, S. mitis, A. measlundii, A. viscosus of the root surface plaque was significantly reduced from I week to 8 weeks after antimicrobial varnish treatment, but showed generally increasing tendency in control group. 3. Gingival crevicular fluid antibody titers were significantly reduced from 1 or 2 weeks to 4 weeks after antimicrobial varnish treatment.
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WDM-PON Link에서 upstream, transmission 성능 향상에 대한 연구
권혁춘,정구익,하상진,한상국 연세대학교 전파통신연구소 2001 電波通信論文誌 Vol.5 No.1
본 논문에서는 파장 분할 WDM-PON 구조를 제안하였으며, CW source를 가지고 Fabry-Perot laser에 injection 시키는 방법을 사용하여 4 channel 155Mbps를 20km upstream 전송하여 분석해 보았다. 제안된 WDM-PON 시스템에서의 이 injection locking 방법은 약 -7dBm ∼ -4dBm 정도의 높은 출력 파워를 제공하였고, 155Mbps 전송시 BER=10-9에서 receiver sensitivity 는 -38dBm정도를 유지하였다. 또한 제안된 구조에서 CW source로 파장 분할된 LED와 FP laser를 사용하여 각각에 대한 시스템에서의 성능을 비교 분석해 보았다. In this paper, we propose a spectrally sliced WDM-PON architecture and analyze the upstream transmission of 4 channels 155Mbps signals by 25km using an injection locking method of Fabry-Perot laser as a CW source. For a proposed WDM-PON system, This injection locking method provides high output power of -7dBm ∼ -4dBm and satisfies receiver sensitivity -38dBm for 10-9 Bit Error Rate for 155Mbps transmission. Also, we compare performances using spectrum-sliced LED and FP laser respectively as CW source for a proposed WDM-FON system.
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김병현,권혁춘 大韓齒科保存學會 1998 Restorative Dentistry & Endodontics Vol.23 No.1
The physical properties of polymer are greatly influenced by the extent to which resin cures. The presence of unreacted monomer can have a plasticizing effect on the polymer, thereby altering the physical and mechanical properties of dentin bonding agent(DBA). If the DBA does not polymerize sufficiently, it will leave a weak bonding layer and lead to lower bond strength. The purpose of this study was to evaluate te shear bond strengths(SBS) and the degree of conversion(DC) of 4 commercialy avilable dentin bonding systems which are composed of 2 multi-bottle systems [Scotchbond Multi-Purpose(SMP), AeliteBond(AB)] and 2 one-bottle systems [SingleBond(SB), One-Step(OS)]. For shear bond strength measurement, labial surfaces of freshly extracted bovine incisors were ground with #600 grit SiC paper to expose dentin. Four different groups of samples were formed, with 10 samples being made for each of the 4 commercial DBA in each group according to the curing sequences of DBA and overlayer thickness of composites:Group Ⅰ (standard cure and 1㎜ thick composites):The DBA was light cured and the composites of 1㎜ thickness was applied;Group Ⅱ (standard cure and 2㎜ thick composites):The DBA was light cured and the composites of 2㎜ thickness was applied;Group Ⅲ(simultaneous cure and 1㎜ thick composites):The DBA was not light-cured and simultaneously cured with composites of 1㎜ thickness;Group Ⅳ(simultaneous cure and 2㎜ thick composites):The DBA was not light-cured and simultaneously cured with composites of 2㎜ thickness. The SBS was measured immediately after the composites was bonded to the bovine dentin using an Instron machine. The DC of the DBA as examined in a thin film under simulated conditions of the experimental groups according to the curing sequences and overlayer thickness of composites in the SBS test. using a Fourier transform Infrared(FTIR) spectrometer. The following results were obtained from SBS tests and DC measurements 1. In SBS tests, the multi-bottle DBA(SMP, AB) had a generally higher bond strength values than the one bottle DBA(SB, OS). In DC measurements, the one bottle DBA(SB, OS) had a significantly higher DC than the multi-bottle DBA(SMP, AB). 2. In all DBAs except OS, there was no significant difference between the bond strength of group Ⅰ(standad cure and 1㎜ thick composites) and that of group Ⅲ(simultaneous cure and 1㎜ thick composites). SMP, SB in Group Ⅰ had a significantly higher DC than those in group Ⅲ, but AB, OS in group Ⅰ had a significantly lower DC than those in group Ⅲ 3. All DBAs in Goup Ⅱ(standard cure and 2㎜ thick composites) had significantly higher bond strength and DC than those in Group Ⅳ(simultaneous cure and 2㎜ thick composites). 4. In all DBAs, there was no significantly different SBS and DC between Group Ⅰ and Group Ⅱ, but all DBAs in Group Ⅲ had significantly higher SBS and DC than those in Group Ⅳ.
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2급와동 광중합 복합레진의 충전방법에 따른 변연누출에 관한 실험적 연구
김경현,권혁춘 大韓齒科保存學會 1993 Restorative Dentistry & Endodontics Vol.18 No.1
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