• 한국응용과학기술학회지
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• 제20권1호
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• pp.8-19
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• 2003

Environmental friendly acrylics/urea high-solid paints (BEHCU) were prepared through the curing reaction of acrylics resin(BEHC) containing 70wt% of solids content and butylated urea curing agent. BEHC was synthesized by addition copolymerization of caprolactone acrylate(CLA), 2-hydroxypropyl methacrylate(2-HPMA), ethyl methacrylate, and n-butyl acrylate. The addition polymerization of these monomers, especially including flexible CLA monomer and 2-HPMA monomer with OH funtional group, under appropriate reaction conditions resulted in polymers with controlled glass transition temperature($T_g$) and crosslinking density. The molecular weight($M_w$) of these polymers(BEHCs) was 2940${\sim}$3240 and polydispersity ($M_w/M_n$) was in the range of 1.61${\sim}$1.72. The viscosity and the molecular weight of these acrylic resins increased with increasing $T_g$. The coated films were prepared using curing reaction between BEHC resin and butylated urea curing agent at 100$^{\circ}C$ for 30 minutes. Our experimental resulted showed that enhancement of the coating properties such as adhesion, flexibility, impact resistance, water resistance, and abrasion resistance could be expected through introducing CLA component in acrylic resin for the high-solid content acrylics/urea coatings.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.337-342
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• 1997

Dental implant has been increasingly used to recover the masticatory unction of tooth. It has been well known that the success of dental implant is heavily dependent on initial stability and long-term osseointegration due to optimal stress distribution in the surrounding bones. The role of periodontal ligament, removed during operation, is to absorb impact force and to distribute them to alveolar bone. or this reason, the study for artificial periodontal ligament has become an important issue in this field. In this study, chitosan was coated on dental implant or the purpose of replacing the role of intact periodontal ligament. The results by experiment and FEM analysis showed : I) Initial stability of dental implant was significantly increased(35%) when the implant was coated with chitosan. II) The coated implant showed higher impact absorption, more even stress distribution and lower stress magnitude under impact force than uncoated implant. Accordingly, the micro-fracture of the surrounding bones due to impact force would be lessened by chitosan coating on dental implant.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.362-363
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• 2012

A new cross-linkable polymer, cross-linked d-PBAB, which has the triphenylamine as the hole transporting moiety and ethynyl group as the thermal cross-linker is firstly synthesized by the combination of anionic polymerization and deprotection process. The thermal cross-linking reaction was performed at $240^{\circ}C$ for 50 min and cross-linked d-PBAB layer showed smooth surface and is not soluble at organic solvent under spin-coating of emitting layer (EML). The solution-processed PLED which was fabricated with cross-linked d-PBAB as HTL showed approximately two times higher Lmax and four times higher LEmax than those obtained from PLED with PEDOT:PSS as the HTL. These result is ascribed to better ability of cross-linked d-PBAB to block electrons and to prevent exciton-quenching than those of PEDOT : PSS at the EML interface. This results strongly suggested that cross-linked d-PBAB can be a promising material to replace conventional PEDOT : PSS. It can be suspected that PLEDwith cross-linked d-PBAB would show longer lifetime compared with that of PLED with PEDOT : PSS, and thus further studies are under investigation.

• The Journal of Advanced Prosthodontics
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• 제8권6호
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• pp.504-510
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• 2016

PURPOSE. Polyamide polymers do not provide sufficient bond strength to auto-polymerized resins for repairing fractured denture or replacing dislodged denture teeth. Limited treatment methods have been developed to improve the bond strength between auto-polymerized reline resins and polyamide denture base materials. The objective of the present study was to evaluate the effect of surface modification by acetic acid on surface characteristics and bond strength of reline resin to polyamide denture base. MATERIALS AND METHODS. 84 polyamide specimens were divided into three surface treatment groups (n=28): control (N), silica-coated (S), and acid-treated (A). Two different auto-polymerized reline resins GC and Triplex resins were bonded to the samples (subgroups T and G, respectively, n=14). The specimens were subjected to shear bond strength test after they were stored in distilled water for 1 week and thermo-cycled for 5000 cycles. Data were analyzed with independent t-test, two-way analysis of variance (ANOVA), and Tukey's post hoc multiple comparison test (${\alpha}=.05$). RESULTS. The bond strength values of A and S were significantly higher than those of N (P<.001 for both). However, statistically significant difference was not observed between group A and group S. According to the independent Student's t-test, the shear bond strength values of AT were significantly higher than those of AG (P<.001). CONCLUSION. The surface treatment of polyamide denture base materials with acetic acid may be an efficient and cost-effective method for increasing the shear bond strength to auto-polymerized reline resin.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3109-3114
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• 2010

Flexible composite films of $V_2O_5$ and conductive polypyrrole ($V_2O_5$/PPy) were grown by facile electrochemical polymerization, wherein an anodization potential was applied to the substrate electrode in an electrolyte solution containing pyrrole monomer and dispersed $V_2O_5$ particles. The coating of polypyrrole (PPy) on the surface of $V_2O_5$ particles was induced by the oxidative catalytic action of $V_2O_5$ during the electrochemical polymerization of pyrrole. PPy in the composite film connects the isolated $V_2O_5$ particles. This results in the formation of conductive networks in the composite film cathode, thereby enhancing the Li+ ion diffusion to the surface of the isolated $V_2O_5$ particles and thus increasing the accessibility of the $Li^+$ ions. The specific capacity tests of the Li rechargeable batteries revealed that the discharge capacity of this composite film cathode was higher, i.e., $497\;mAhg^{-1}$, than that of $V_2O_5$/PPy powder or pristine $V_2O_5$.

• Journal of Pharmaceutical Investigation
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• 제34권3호
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• pp.177-183
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• 2004

Recently, studies on intranasal mucosa delivery of influenza vaccine have been actively developed because of lack of pain and ease of administration. We studied on preparation of nanoparticle delivery system using biodegradable polymer as a poly(DL-lactide-co-glycolide) (PLGA) and their binding characteristics with vaccine. Three kinds of PLGA nanoparticles were prepared by spontaneous emulsification solvent diffusion (SESD) method using sodium dodecyl sulfate and sodium laurate as an anionic surfactant and Lutrol F68 (polyethylene glycol-block-polypropylene glycol copolymer) as a nonionic surfactant. The 5-aminofluorescein labeled vaccine was coated on the surface of nanoparticles by ionic complex. The complexes between vaccine and nanoparticles were confirmed by change of the size. After vaccine coating on the surface of anionic nanoparticles, particle size was increased from 174 to 1,040 nm. However the size of nonionic nanoparticles was not more increased than size of anionic nanoparticles. The amount of coated vaccine on the surface of PLGA nanoparticles was $14.32\;{\mu}g/mg$ with sodium dodecyl sulfate, $12.41\;{\mu}g/mg$ with sodium laurate, and $9.47{\mu}g/mg$ with Lutrol F68, respectively. In conclusion, prepared nanoparticles in this study is possible to use as a virus-like nanoparticles and it could be accept in the field of influenza vaccine delivery system.

• 한국구조물진단유지관리공학회 논문집
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• 제17권2호
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• pp.117-123
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• 2013

원형 구조물의 보수/보강 및 FRP를 구조부재로 활용한 신설 구조물 시공을 위해서는 일정한 곡률반경을 갖는 곡면 FRP 부재가 요구된다. 그러나 현재까지 FRP 곡면부재는 수작업 (hand-lay-up) 또는 필라멘트 와인딩 (filament winding) 작업에 의해서만 생산이 가능하였으며, 대량 연속생산에는 한계가 있다. 또한 일반적으로 인발성형법 (pultrusion method)으로 생산된 FRP 부재가 상대적으로 물리적 특성이 우수한 것으로 알려져 있다. 따라서 FRP 부재를 일정곡률을 유지하며 인발로 뽑아낼 수 있는 신개념의 곡면 FRP 부재 인발성형법 제안 및 성형장비를 개발, 곡면 FRP 제품을 생산하였으며, 본 연구에서는 곡면 FRP 부재를 이용한 구조물 보수/보강시 야기될 수 있는 FRP와 콘크리트 부착면의 동결융해 영향을 분석하였다.

• The Journal of Advanced Prosthodontics
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• 제1권2호
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• pp.68-74
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• 2009

STATEMENT OF PROBLEM. When veneering composite resin-metal restoration is prepared, the fact that bond strength between Ti and composite resin is relatively weak should be considered. PURPOSE. The purpose of this study is to evaluate the shear bond strength between the veneering composite resin and commercial pure (CP) Ti / Ti-6Al-4V alloy according to the method of surface treatment. MATERIAL AND METHODS. The disks were cast by two types of metal. Their surfaces were treated by sandblasting, metal conditioner, TiN coating and silicoating respectively. After surface treatment, the disks were veneered by composite resin (Tescera$^{TM}$, Bisco, USA) which is 5 mm in diameter and 3 mm in thickness. The specimens were stored in water at $25^{\circ}C$ for 24 hours, and then evaluated for their shear bond strength by universal testing machine (STM-$5^{(R)}$, United Calibration, USA). These values were statistically analyzed. RESULTS. 1. All methods of surface treatment were used in this study satisfied the requirements of ISO 10477 which is the standard of polymer-based crown and bridge materials. 2. The metal conditioner treated group showed the highest value in shear bond strength of CP Ti, silicoated group, TiN coated group, sandblasted group, in following order. 3. The silicoated group showed the highest value in shear bond strength of Ti-6Al-4V alloy, metal conditioner treated group, sandblasted group, TiN coated group, in following order. CONCLUSION. Within the limitations of this study, all methods of surface treatment used in this study are clinically available.

• Korean Chemical Engineering Research
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• 제49권4호
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• pp.498-504
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• 2011

본 연구는 폴리이미드와 폴리이서설폰 중공사막을 이용하여 매립가스의 메탄 회수를 위한 메탄과 질소에 대한 투과도와 선택도를 실험하였다. 폴리이미드와 폴리이서설폰 소재를 건/습식 상전이 법을 이용하여 중공사 형태로 제조하고 표면 실리콘 코팅 후 모듈을 제조하였다. 전자주사 현미경 관찰을 이용하여 제조된 중공사 막의 구조가 치밀한 표면과 망상구조의 비대칭으로 형성된 것을 확인하였다. 압력과 온도가 증가함에 따라 메탄과 질소의 투과도는 증가하였으나 선택도($CH_4/N_2$)는 감소하는 것으로 나타났다. Air gap이 증가할수록 메탄과 질소의 투과도는 감소하였으며 용매치환을 한 중공사막의 투과도는 3.2~7.0배 증가하였다.

• Elastomers and Composites
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• 제34권2호
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• pp.128-134
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• 1999

타이어 코드용 강철선을 RF 플라즈마를 이용한 acetylene 및 butadiene 가스의 플라즈마 중합으로 코팅하였으며, 타이어용 고무와의 접착력을 TCAT 또는 T-test로 측정하였다. 강철선의 접착력은 사용된 gas, plasma power, 코팅시간 및 가스 압력에 따라 측정하였으며, 플라즈마 중합에 앞서 Ar 플라즈마 에칭으로 타이어 코드를 세척하였다. 또한 $80^{\circ}C$의 증류수에서 7일간 노화시켜 접착력 저하를 고찰하였으며, 접착력 시험 후 타이어 코드 표면을 SEM으로 분석하여 파괴거동을 규명하고자 하였다. 가장 우수한 접착력은 acetylene의 경우 20W, 2분, 25mtorr에서, 그리고 butadiene의 경우는 l0W, 4분, 25mtorr에서 얻을 수 있었으며, Ar 에칭에 의한 접착력 변화는 없었다. 노화에 의한 접착력 저하는 없었으며, 도리어 증가하는 현상을 보였다. SEM 분석에서 강철선의 높은 거칠기와 플라즈마 코팅의 얇은 두께로 인하여 파괴거동 규명에는 한계가 있었다.