• Proceedings of the KACD Conference
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• 2008.05a
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• pp.213-223
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• 2008

The objective of this study was to compare dentin shear bond strength (DSBS) of dentin bonding agents (DBAs) cured with a plasma arc (PAC) light curing unit (LCU) and those cured with a light emitting diode (LED) LCU. Optical properties were also analyzed for Elipar freelight 2 (3M ESPE); LED LCU, Apollo 95E (DMT Systems); PAC LCU and VIP Junior (Bisco); Halogen LCU. The DBAs used for DSBS test were Scotchbond Multipurpose (3M ESPE), Singlebond 2 (3M ESPE) and Clearfil SE Bond (Kuraray). After DSBS testing, fractured specimens were analyzed for failure modes with SEM. The total irradiance and irradiance between 450 nm and 490 nm of the LCUs were different. LED LCU showed narrow spectral distribution around its peak at 462 nm whereas PAC and Halogen LCU showed a broad spectrum. There were no significant differences in mean shear bond strength among different LCUs (P > 0.05) but were significant differences among different DBAs (P < 0.001).

• Restorative Dentistry and Endodontics
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• v.33 no.3
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• pp.213-223
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• 2008

The objective of this study was to compare dentin shear bond strength (DSBS) of dentin bonding agents (DBAs) cured with a plasma arc (PAC) light curing unit (LCU) and those cured with a light emitting diode (LED) LCU. Optical properties were also analyzed for Elipar freelight 2 (3M ESPE); LED LCU, Apollo 95E (DMT Systems); PAC LCU and VIP Junior (Bisco); Halogen LCU. The DBAs used for DSBS test were Scotchbond Multipurpose (3M ESPE), Singlebond 2 (3M ESPE) and Clearfil SE Bond (Kuraray). After DSBS testing, fractured specimens were analyzed for failure modes with SEM. The total irradiance and irradiance between 450 nm and 490 nm of the LCUs were different. LED LCU showed narrow spectral distribution around its peak at 462 nm whereas PAC and Halogen LCU showed a broad spectrum. There were no significant differences in mean shear bond strength among different LCUs (P > 0.05) but were significant differences among different DBAs (P < 0.001)

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.4
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• pp.455-463
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• 2018

The purpose of this study was to evaluate the effect of the intracanal medicaments on the push-out bond strength of the calcium silicate-based materials. Forty extracted single-root human mandibular premolars were sectioned below cementoenamel junction. Standardized root canal dimension was obtained with a parallel post drill. The specimens were randomly divided into a control group (no medicament), and experimental groups received medicaments with either CH (calcium hydroxide), DAP (double antibiotic paste; a mixture of ciprofloxacin and metronidazole), or TAP (triple antibiotic paste; a mixture of minocycline, ciprofloxacin and metronidazole). Following removal of medicaments with irrigation, roots were cut into sections with 1-mm-thickness. Thereafter, calcium silicate-based materials are applied to the specimens : (i) ProRoot MTA$^{(R)}$ and (ii) Biodentine$^{(R)}$. A push-out bond strength was measured and each specimen was examined to evaluate failure mode. Intracanal medication using CH significantly increased the bond strength to the root dentin. But there are no significant differences on the bond strength of ProRoot MTA$^{(R)}$ or Biodentine$^{(R)}$ among TAP, DAP and control groups. The dislodgement resistance of Biodentine$^{(R)}$ from root dentin was significantly higher than that of ProRoot MTA$^{(R)}$ regardless of the type of intracanal medicaments.

• Restorative Dentistry and Endodontics
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• v.33 no.5
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• pp.419-427
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• 2008

This study analyzed the influence of dental adhesive/primer on the bond strength between indirect resin composite and the resin cement. Seventy disc specimens of indirect resin composite (Tescera Dentin, Bisco) were fabricated. And bonding area of all specimens were sandblasted and silane treated for one minute. The resin cements were used with or without application of adhesive/primer to bonding area of indirect resin restoration, Variolink-II (Ivoclar-Vivadent) : Exite DSC, Panavia-F (Kuraray) : ED-Primer, RelyX Unicorn (3M ESPE) Single- Bond, Duolink (Risco) : One-step, Mulitlink (Ivoclar-Vivadent) : Multilinh Primer. Shear bond strength was measured by Instron universal testing machine. Adhesive application improved shear bond strength (p<0.05) But Variolink II and Panavia-F showed no statistically significant difference according to the adhesive application. With the above results, when resin inlay is luted by resin cement it seems that application of dental adhesive/primer is necessary in order to improve the bond strength.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.95-98
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• 2001

Co-cured joining method is an efficient joining technique because both curing and bonding processes for the composite structures can be achieved simultaneously. It requires neither an adhesive nor a surface treatment of the composite adherend because the excess resin, which is extracted from composite materials during consolidation, accomplishes the co-cured joining process. In this paper, we considered three bond parameters, affecting tensile load bearing capacity of the co-cured single and double lap joints. Filially, we nave presented optimal bonding conditions for co-cured single and double lap joints with steel and composite adherends under tensile loads.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.186-186
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• 2011

[100] 방향으로 4$^{\circ}$ 기울어진 Si(001)-2${\times}$1(vicinal surface)을 초고진공하(UHV)에서 청결하게 하고 열처리하면 rebonded-atom을 가진 DB double step과 이 step에 나란한 아홉 개의 dimer를 가진 평균 폭이 4.0 nm인 single-domain의 (001)-2${\times}$1 테라스의 면으로 재구조된다 [그림 a]. 본 연구에서는 이 표면 위에 Sb을 상온에서 증착하여 덮고 후열처리하면(2 ML, 500$^{\circ}C$ 10 분), Sb-dimer가 Si 표면을 한 층 덮고 (001) 테라스의 Sb-dimer 방향이 DA double-step과 수직을 이루는 1${\times}$2 구조를 이룬다는 사실을 STM으로 확인하였다 [그림 b]. 이러한 Sb-passivation의 효과는 표면 Si-dimer의 부분적으로 채워진 dangling-bond를 Sb-dimer의 완전히 채워진 고립쌍(lone-pair)으로 바꿈으로써 표면 자유 에너지를 줄이고, 나아가 계면 Si 층은 bulk에 유사하게 되는 데에 있다. 이 passivation 된 표면은 Ge/Si 등의 heteroepitaxy에 사용할 수 있고, 특히 single-domain을 유지하며 step 방향에 대해 평행인 dimer-row로 이루어져 있어서 원자나 전자의 이동에 비등방적 효과를 증가시킬 것이 예측된다.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2801-2805
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• 2010

A nucleophilic substitution reaction of 4-chloro-7-nitrobenzofurazan (NBF-Cl) with anilines in MeOH-MeCN mixtures was conducted at 25, 35, and $45^{\circ}C$. Based on the higher $\beta_{nuc}$ values (1.0 - 1.6) of the reaction and a good correlation of the rate constants with the reduction potentials of the aniline nucleophiles, the present reaction was initiated by a single electron transfer (SET). After this step, the reaction proceeds through a transition state similar to the normal $S_NAr$-Ad.E pathway.

• Journal of the Korean Magnetic Resonance Society
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• v.11 no.2
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• pp.64-72
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• 2007

[ $^1H$ ] nuclear magnetic resonance (NMR) experiments have been performed at 30 - 300 K and 7 T to investigate dynamics of hydrogen bond network in the single crystal $(NH_4)_3H(SO_4)_2$. The two proton sites, ammonium proton and hydrogen-bond proton, are identified from the $^1H$ NMR MAS spectrum at 340 K. As temperature decreases, the $^1H$ NMR spectrum shifts to the higher frequency side with a larger linewidth. The spectrum at 65 K shows a distinctive change in line shape toward the ferroelectric transition at 63 K. The measured values of $T_1$ for ammonium and hydrogen-bond protons are similar in the whole range of temperature. $T_1$ of $^1H$ NMR shows a gradual decrease down to 120 K and starts to steeply increase below 100 K. Then $T_1$ shows abrupt decrease below 70 K with a sharp minimum at 63 K, where the ferroelectric transition occurs. This temperature dependence of spectrum and $T_1$ clearly prove that the large change in the dynamics of hydrogen bond network is associated with the ferroelectric phase transition at 63 K.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.2
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• pp.181-191
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• 2006

The objectives of this study were to evaluate the tensile strength of resin-infiltrated demineralized dentin according to the demineralization time, and to evaluate the tensile strength of hybrid layer that is formed by infiltrating different priming adhesives or primer/adhesive into demineralizd dentin matrix. Seventy five hour-glass shaped dentin specimens were prepared in mid-coronal dentin from extracted human molars. Thirty specimens were distributed into three groups according to demineralization time - 2 hours, 4 hours and 8 hours. Each specimen was placed in primer/adhesive of All-Bond 2 for 5 hours of infiltration. Another forty-five specimens of them were demineralized in 37% phosphoric acid for 4 hours. They were randomly assigned to three experimental groups - AB, SB and OS - to designate All-Bond 2, Single Bond and One-Step. Each specimen was placed in one of three different adhesives for 5 hours of infiltration. The specimens were visible light-cured for 5 minutes, and then stored for 24 hours in distilled water at $37^{\circ}C$. After that, microtensile bond strength for each specimen was measured, and the fractured surfaces were then observed by SEM. The data were statistically analysed by one-way ANOVA and Tukey's multiple comparison test and Bonferroni's multiple comparison test. The results were as follows; 1. Tensile strength of the group demineralized for 4 hours was significantly higher than that of groups demineralized for 2 hours and 8 hours (P < .01). 3. Tensile strength of the AB group was significantly higher than that of the SB group and OS group (P < .01).

• Steel and Composite Structures
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• v.23 no.6
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• pp.727-736
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• 2017

The application of carbon fiber reinforced polymer (CFRP) in steel structures primarily includes two categories, i.e., the bond-critical application and the contact-critical application. Debonding failure and buckling failure are the main failure modes for these two applications. Conventional electrometric techniques may not provide precise results because of the limitations associated with single-point contact measurements. A nondestructive full-field measurement technique is a valuable alternative to conventional methods. In this study, the digital image correlation (DIC) technique was adopted to investigate the bond behavior and buckling behavior of CFRP-steel composite members. The CFRP-to-steel bonded joint and the CFRP-strengthened square hollow section (SHS) steel column were tested to verify the suitability of the DIC technique. The stereo-DIC technique was utilized to measure continuous deformation. The bond-slip relationship of the CFRP-to-steel interface was derived using the DIC data. Additionally, a multi-camera DIC system consisting of four stereo-DIC subsystems was proposed and applied to the compressive test of CFRP-strengthened SHS steel column. The precise buckling location and CFRP delamination of the CFRP-strengthened SHS steel column were identified. The experimental results confirm that the stereo-DIC technique can provide effective measurements for investigating the behaviors of CFRP-steel composite members.