• 한국방재학회 논문집
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• 제2권2호
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• pp.105-113
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• 2002

강합성 교량은 자중의 감소, 강성의 증대, 장지간의 적용 등의 재료적 특성에 힘입어 1920년대 이래로 사용되어져 왔다. 그러나 연속교의 경우 내부지점부에서 발생하는 부모멘트로 인하여 콘크리트 부분에 균열이 생기고 콘크리트의 건조수축이나 Creep으로 인한 문제들이 제기 됨에 따라 슬랩앵커를 이용한 부분합성교량이 제기 되었다. 부분합성의 경우 어느 정도의 슬립을 허용하여 이러한 문제를 극복할 수 있다. 본 연구에서는 슬랩앵커의 탄성구간에서의 초기 강성값을 실험을 통하여 알아내고, 단순지지인 경우와 연속교의 경우에 대하여 범용 프로그램을 이용하여 슬래브와 강재를 연결시키는 조인트 요소의 강성값을 변화시켜 전단연결재의 강성값에 따른 합성정도와 내부지점부의 콘크리트 슬래브의 인장응력이 어떤 변화양상을 나타내는지 파악하고자 한다.

• 접착 및 계면
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• 제21권1호
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• pp.27-33
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• 2020

유리섬유강화 복합재료 (GFRC)의 표면거칠기에 따른 에폭시 접착제의 접착강도를 평가하였고 최적의 표면거칠기를 선정하였다. 서로 다른 입자크기의 알루미나 (Al2O3) 입자를 GFRC의 표면에 분사하였고 이를 통하여 서로 다른 표면거칠기를 부여하였다. 표면거칠기를 정량화 하였고 표면거칠기에 따른 표면관찰을 진행하였다. 각 표면거칠기에 따른 접촉각을 측정하였고 이를 통하여 표면에너지를 계산하였으며, 에폭시 접착제와의 접착일을 계산 및 비교하여 접착력을 예측하였다. 단일랩전단 시험을 통해 접착강도를 평가하였고 거칠기에 따라 접착강도가 증가된다는 것을 확인하였다. 박리 후 표면을 관찰해 보았을 때 기지재인 GFRC의 박리 정도가 다른 것을 확인하였고 최종적으로 표면거칠기의 최적조건을 확인할 수 있었다.

• The Journal of Advanced Prosthodontics
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• 제12권1호
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• pp.22-32
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• 2020

PURPOSE. The aim of this study was to evaluate the microshear bond strength (µSBS) of four computer-aided design/computer-aided manufacturing (CAD/CAM) blocks repaired with composite resin using three different surface treatment protocols. MATERIALS AND METHODS. Four different CAD/CAM blocks were used in this study: (1) flexible hybrid ceramic (FHC), (2) resin nanoceramic (RNC), (c) polymer infiltrated ceramic network (PICN) and (4) feldspar ceramic (FC). All groups were further divided into four subgroups according to surface treatment: control, hydrofluoric acid etching (HF), air-borne particle abrasion with aluminum oxide (AlO), and tribochemical silica coating (TSC). After surface treatments, silane was applied to half of the specimens. Then, a silane-containing universal adhesive was applied, and specimens were repaired with a composite, Next, µSBS test was performed. Additional specimens were examined with a contact profilometer and scanning electron microscopy. The data were analyzed with ANOVA and Tukey tests. RESULTS. The findings revealed that silane application yielded higher µSBS values (P<.05). All surface treatments were showed a significant increase in µSBS values compared to the control (P<.05). For FHC and RNC, the most influential treatments were AlO and TSC (P<.05). CONCLUSION. Surface treatment is mandatory when the silane is not preferred, but the best bond strength values were obtained with the combination of surface treatment and silane application. HF provides improved bond strength when the ceramic content of material increases, whereas AlO and TSC gives improved bond strength when the composite content of material increases.

• 폴리머
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• 제24권4호
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• pp.499-504
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• 2000

고강도 PAN계 탄소섬유를 양극산화하여 섬유의 표면 관능기와 표면 자유에너지, 그리고 최종 복합재료의 기계적 특성 향상에 미치는 영향을 고찰하였다. FT-IR과 XPS 측정 결과, 양극산화에 의해 형성된 섬유 표면의 산소 관능기는 섬유의 표면 에너지와 복합재료의 층간 전단강도 (ILSS)에 큰 영향을 주는 것으로 나타났다. 그리고 젖음액의 wicking rate에 근거한 접촉각 측정에서 탄소섬유의 양극산화는 표면 자유에너지의 극성 요소를 크게 증가시키며, 이것은 표면 에너지 관점에서 살펴볼 때 좋은 젖음성이 최종 복합재료의 섬유와 에폭시 수지 매트릭스사이의 계면결합력 향상에 중요한 역할을 하는 것으로 나타났다. 또한 본 연구에서는 섬유 표면의 $O_{1s}$ $C_{11}$ ratio 또는 극성 요소와 복합재료의 ILSS사이에서 직선적인 상관관계를 나타낼 수 있었다.다.

• The Journal of Advanced Prosthodontics
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• 제16권2호
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• pp.105-114
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• 2024

PURPOSE. This study aimed to evaluate the effect of pretreatment of three different universal adhesives (Single Bond Universal [SBU], All-Bond Universal [ABU], and Prime&Bond universal [PBU]) on the bonding durability of an adhesive (Panavia F 2.0, PF) and a conventional (Duo-Link, DL) resin cements to air-abraded zirconia. MATERIALS AND METHODS. Rectangular-shaped zirconia specimens were prepared. The chemical composition and surface energy parameters of the materials were studied by Fourier transform infrared spectroscopy and contact angle measurement, respectively. To evaluate resin bonding to the zirconia, all the bonding specimens were immersed in water for 24 h and the specimens to be aged were additionally thermocycled 10000 times before the shear bond strength (SBS) test. RESULTS. The materials showed different surface energy parameters, including the degree of hydrophilicity/hydrophobicity. While the DL/CON (no pretreatment) showed the lowest SBS and a significant decrease in the value after thermocycling (P < .001), the PF/CON obtained a higher SBS value than the DL/CON (P < .001) and no decrease even after thermocycling (P = .839). When the universal adhesives were used with DL, their SBS values were higher than the CON (P < .05), but the trend was adhesive-specific. In conjunction with PF, the PF/SBU produced the highest SBS followed by the PF/ABU (P = .002), showing no significant decrease after thermocycling (P > .05). The initial SBS of the PF/PBU was similar to the PF/CON (P = .999), but the value decreased after thermocycling (P < .001). CONCLUSION. The universal adhesive pretreatment did not necessarily show a synergistic effect on the bonding performance of an adhesive resin cement, whereas the pretreatment was beneficial to bond strength and durability of a conventional resin cement.

• 접착 및 계면
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• 제6권3호
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• pp.19-25
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• 2005

합성 고무계 점착제는 일반적으로 SIS나 SBS 블록 공중합체와 점착부여수지, 가소제, 기타 첨가제를 함유한다. SIS/SBS 계 점착제는 우수한 접착력에도 불구하고 내용제성이나 내열성이 낮아서 그 사용에 한계가 있다. 이에 이러한 단점을 보완하고자 SIS/SBS 점착제에 가교제, 광개시제를 주성분으로 하는 자외선 경화 시스템을 도입하였다. 제조된 점착제는 thiol-ene 광중합 반응에 의해 가교하였으며 점착제의 프로브 택(probe tack), 박리강도(peel strength) 전단접착파괴온도(shear adhsion failure temperature, SAFT)를 측정하여 UV 경화형 점착특성을 고찰하였다. 또한 UV 경화형 점착제의 택 성질을 프로브 택을 이용하여 프로브 재료별, 점착제의 두께별의 영향을 살펴보았고 접촉각 측정을 통해 점착제 표면 변화를 살펴보았다.

• 대한치과보철학회지
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• 제44권5호
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• pp.594-605
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• 2006

Statement of problem: Modification of titanium implant surface has potential to ensure clinically favorable performance that several surface modification technologies have been introduced. Among the methods. anodizing method and sol-gel hydroxyapatite coating method have gained much interest due to its roughness and chemical composition of the coating layer, but more of its biocompatibility result is required. Purpose : The purpose of this study was to compare bone-implant interface shear strength of four different surface treated implants as time elapsed. Resonance frequency analysis(RFA) and removal torque measurement methods were employed to measure implant stability at one week and six week after implantation. Material and method: A total of 80 screw-shaped implant [20 machined, 20 resorbable media blasted(RBM), 20 anodized, and 20 anodized+hydroxyapatite sol-gel coated] were prepared, and one of each group was implanted in the tibia of a New Zealand white rabbit that total 20 of them were used. In order to test the implant stability and implant-tissue interface contact changing in the bone bed, each 10 rabbit were sacrificed 1 week and 6 week later while resonance frequency and removal torque were measured. One-way analysis of variance and the Tukey test were used for statistical analysis. Results : The results were as follows. 1. There was no statistically significant difference of implant stability quotients(ISQ) value in RFA between individual groups after 1 week of implantation and 6 weeks(p>0.05). But, there was statistically significant increase of ISQ value in 6 weeks group compared to 1 week group(p<0.05). 2. There was no statistically significant difference in removal torque analysis between individual groups after 1 week of implantation and 6 weeks(p>0.05). but there was statistically significant increase in all 4 groups after 6 weeks compared to 1 week later(p<0.05). 3. There was no statistically significant difference in removal torque analysis between anodized group and HA coating after anodic oxidation 6 weeks later(p>0.05), but significant difference was appeared in both groups compared to RBM group and smooth-machined group(p<0.05). Conclusions : It can be suggested that changes in surface characteristics affect bone reactions. Anodized and anodized+hydroxyapatite sol-gel coating showed significantly improved bone tissue response to implants, but further study on the effect of hydroxyapatite dissolution is needed.

• 한국수자원학회논문집
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• 제49권11호
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• pp.931-939
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• 2016

국보 285호인 반구대 암각화는 EL.53~57 m에 위치해 있으며, 하류에 설치된 사연댐의 만수위 EL.60 m로 인해 매년 5~6개월 동안 침수와 노출이 반복되어 훼손이 심화되고 있다. 본 연구에서는 물과의 접촉을 차단시켜 암각화를 보존하는 방안으로서, 암각화 전면에서 약 80 m 떨어진 곳에 약 440 m의 차수형 제방을 설치하고 기존 하폭에 준하는 수로를 개설하는 생태제방안을 제안하였다. 이 안의 타당성을 검토하기 위해 저수지와 하천의 흐름특성을 고려할 수 있는 수리모형을 1:50축척으로 제작하여, 수로변경에 따른 신설 제방구간과 상 하류 대곡천의 수리학적 변화를 분석하였다. 연구결과, 사연댐 여수로를 EL. 60 m와 EL. 54 m로 고려한 생태제방 1안과 2안 모두 신설되는 수로에서 유속과 수심변화 등이 크지 않았으며, 허용유속과 소류력 기준으로 판단하면 흙과 돌 등 자연재료로 생태제방 조성이 가능할 것으로 판단된다. 수면경사가 크게 되는 2안이 1안보다 수로 내에서의 유속이 더 빠른 것으로 나타났고, 특히 2안은 유입부 좌안에서 와류가 발생하므로 이에 대한 대책이 필요한 것으로 보인다.

• Restorative Dentistry and Endodontics
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• 제42권3호
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• pp.206-215
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• 2017

Objectives: To determine the combined effect of fatigue cyclic loading and thermocycling (CLTC) on the shear bond strength (SBS) of a resin cement to zirconia surfaces that were previously air-abraded with aluminum oxide ($Al_2O_3$) particles at different pressures. Materials and Methods: Seventy-two cuboid zirconia specimens were prepared and randomly assigned to 3 groups according to the air-abrasion pressures (1, 2, and 2.8 bar), and each group was further divided into 2 groups depending on aging parameters (n = 12). Panavia F 2.0 was placed on pre-conditioned zirconia surfaces, and SBS testing was performed either after 24 hours or 10,000 fatigue cycles (cyclic loading) and 5,000 thermocycles. Non-contact profilometry was used to measure surface roughness. Failure modes were evaluated under optical and scanning electron microscopy. The data were analyzed using 2-way analysis of variance and ${\chi}^2$ tests (${\alpha}=0.05$). Results: The 2.8 bar group showed significantly higher surface roughness compared to the 1 bar group (p < 0.05). The interaction between pressure and time/cycling was not significant on SBS, and pressure did not have a significant effect either. SBS was significantly higher (p = 0.006) for 24 hours storage compared to CLTC. The 2 bar-CLTC group presented significantly higher percentage of pre-test failure during fatigue compared to the other groups. Mixed-failure mode was more frequent than adhesive failure. Conclusions: CLTC significantly decreased the SBS values regardless of the air-abrasion pressure used.