• 한국수소및신에너지학회논문집
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• 제18권4호
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• pp.391-398
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• 2007

The covalently cross-linked sulfonated polyetheretherketone (CL-SPEEK) membrane was prepared by four-step synthesis of sulfonation-sulfochlorination, partial reduction, lithiation, and cross-linking, and its electrochemical and mechanical properties were investigated for water electrolysis application. The prepared ion exchange membranes showed good electrochemical and mechanical properties; proton conductivity of 0.116 S/cm at $80^{\circ}C$, water uptake of 44.6%, ion exchange capacity of 1.75 meq/g-dry-memb., tensile strength of 64.25 MPa and elongation of 61.11%. The membrane electrode assembly (MEA) with homemade membranes were prepared by non-equilibrium impregnation-reduction (I-R) method. Especially, the electrochemical surface area (ESA) and roughness factor of CL-SPEEK electrolyte by cyclic voltammetry method were 23.46 $m^2/g$ and 307.3 $cm^2-Pt/cm^2$, respectively. The prepared MEA was used in the unit cell of water electrolysis and the cell voltage was 1.81 V at 1 A/$cm^2$ and $80^{\circ}C$, with platinum loadings of 1.31 mg/$cm^2$.

• 대한치과기공학회지
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• 제38권1호
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• pp.1-6
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• 2016

Purpose: The present study was to determine the stress distribution of an abutment screw according to implant abutment material. Methods: This study was a tightening torque 10 Ncm, 20 Ncm, set to 30 Ncm, and a titanium alloy (Ti-6Al-4V), PEEK (polyetheretherketone), Endoligns (60% Carbon Fiber Reinforced PEEK) material of the custom abutment titanium alloy (Ti-6Al-4V) the stress distribution in the material of the abutment screw will be evaluated by the finite element analysis. Results: Abutment screw most stress has been concentrated on the interface between the fixture and the abutment was also part of the interface that the threads are started. Depending on the abutment of the abutment screw Material von Mises stress values are shown differently. 10Ncm T10 under the tightening torque of 294.2 MPa, P10 is 562.8 MPa, appeared to E10 is 295.8 MPa, 20Ncm tightening torque under T20 is 581.1 MPa, P20 is 1125 MPa, E20 was shown to 585.1 MPa, 30Ncm tightening torque under T30 is 918.2 MPa, P30 is 1795 MPa, E30 has appeared 925.1 MPa. Conclusion: If the abutment is used as Endoligns, it was confirmed that the abutment screw exhibits of von Mises stress value is similar to the titanium alloy abutment.

• Composites Research
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• 제35권2호
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• pp.86-92
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• 2022

본 연구에서는 접착제를 구성하는 분자 결합 구조의 차이가 열가소성 복합재의 계면 특성에 미치는 영향을 판단하기 위해 진행되었다. 고온 오븐 접합 공정을 이용하여 carbonfiber/polyetherketoneketone(CF/PEKK) 열가소성 복합재료를 융합 접합, polyetheretherketone(PEEK), polyetherimide(PEI) 접착제 접합하였다. 그리고 lap 전단 강도 시험과 디지털 광학 현미경과 주사 전자 현미경을 이용한 파단면 분석, FTIR 분석을 수행하였다. 그 결과, 접착제 접합은 CF/PEKK와 접착제를 구성하는 주요 결합기인 에테르기, 케톤기, 이미드기의 결합이 증가한 인터페이즈를 형성하여 접착 강도를 강화시켰다. 그리고, 에테르기와 케톤기를 더 많이 함유한 PEEK를 사용하는 것이 더 강한 결합력을 갖는 인터페이즈를 형성하여, 복합재의 접착 강도를 향상시켰다.

• The Journal of Advanced Prosthodontics
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• 제15권1호
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• pp.33-43
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• 2023

PURPOSE. This study investigated the physical and mechanical changes in the titanium base of three different hybrid abutment materials after cyclic loading by estimating the post-load reverse torque value (RTV), compressive side fulcrum wear pattern of titanium base, and surface roughness. MATERIALS AND METHODS. A total of 24 dental implants were divided into three groups (n = 8 each): Group Z, LD, and P used zirconia, lithium disilicate, and polyetheretherketone, respectively, for hybrid abutment fabrication. RTV was evaluated after cyclic loading with 50 N for 1.2 × 10⁶ chewing cycles. The compressive sides of the titanium bases were analyzed using a scanning electron microscope, and the roughness of the affected areas was measured using an optical profilometer after loading. Datasets were analyzed using Kruskal-Wallis test followed by Mann-Whitney tests with the Bonferroni correction (α = .05). RESULTS. Twenty-three samples passed the test; one LD sample fractured after 770,474 cycles. Post-load RTV varied significantly depending on the hybridabutment material (P = .020). Group P had a significantly higher median of post-load RTVs than group Z (16.5 and 14.3 Ncm, respectively). Groups LD and P showed minor signs of wear, and group Z showed a more pronounced wear pattern. While evaluating compressive side affected area roughness of titanium bases, lower medians were shown in group LD (Ra 0.16 and Rq 0.22 ㎛) and group P (Ra 0.16 and Rq 0.23 ㎛) than in group Z (Ra 0.26 and Rq 0.34 ㎛); significant differences were found only among the unaffected surface and group Z. CONCLUSION. The hybrid abutment material influences the post-load RTV. Group Z had a more pronounced wear pattern on the compressive side of titanium base; however, the surface roughness was not statistically different among the hybridabutment groups.

• 한국표면공학회지
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• 제56권4호
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• pp.273-282
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• 2023

In this study, the surface of Polyetheretherketone (PEEK) disks was modified to have a hydrophilic surface by applying a coating of Polyethylene glycol (PEG), Hyaluronic acid(HA), and Poly-Dopamine(PDA). The investigation aimed to examine whether the coated surfaces showed enhanced bioactivity for orthopedic applications compared to the pure PEEK. The microstructure, surface characteristics, and wettability of PEEK coated with PEG, HA, and PDA were analyzed using scanning electron microscopy(SEM), FT-IR spectrophotometer, Roughness Measurement System, Micro-Vickers, and Contact angle measurement. The mechanical properties were analyzed using a tensile testing machine, while the MTT assay for cell activity was analyzed using a microplate reader to measure optical density. According to the SEM and FT-IR results, the composition and crystal structure of PEG, HA and PDA coated surface were verified. Also, roughness, hardness, and contact angle were all improved in the coating group compared to the pure PEEK. We checked the HepG2 cell proliferation by using MTT assay on 7th days. In MTT assay results, HepG2 cell proliferation was increased with time, at 7 days, cell viability on discs coated with PDA was significantly higher than pure PEEK, PEG, HA coated group. PDA coated PEEK exhibited the highest surface roughness, hardness, contact angle, and cell activity. The mechanical properties were not affected by the presence of the coating.

• Journal of Korean Neurosurgical Society
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• 제60권6호
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• pp.611-619
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• 2017

Objective : In addition to bone bridging inside a cage or graft (intragraft bone bridging, InGBB), extragraft bone bridging (ExGBB) is commonly observed after anterior cervical discectomy and fusion (ACDF) with a stand-alone cage. However, solid bony fusion without the formation of ExGBB might be a desirable condition. We hypothesized that an insufficient contact area for InGBB might be a causative factor for ExGBB. The objective was to determine the minimal area of InGBB by finite element analysis. Methods : A validated 3-dimensional, nonlinear ligamentous cervical segment (C3-7) finite element model was used. This study simulated a single-level ACDF at C5-6 with a cylindroid interbody graft. The variables were the properties of the incorporated interbody graft (cancellous bone [Young's modulus of 100 or 300 MPa] to cortical bone [10000 MPa]) and the contact area between the vertebra and interbody graft (Graft-area, from 10 to $200mm^2$). Interspinous motion between the flexion and extension models of less than 2 mm was considered solid fusion. Results : The minimal Graft-areas for solid fusion were $190mm^2$, $140mm^2$, and $100mm^2$ with graft properties of 100, 300, and 10000 MPa, respectively. The minimal Graft-areas were generally unobtainable with only the formation of InGBB after the use of a commercial stand-alone cage. Conclusion : ExGBB may be formed to compensate for insufficient InGBB. Although various factors may be involved, solid fusion with less formation of ExGBB may be achieved with refinements in biomaterials, such as the use of osteoinductive cage materials; changes in cage design, such as increasing the area of polyetheretherketone or the inside cage area for bone grafts; or surgical techniques, such as the use of plate/screw systems.

• 대한방사성의약품학회지
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• 제2권2호
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• pp.123-131
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• 2016

Increasing clinical demand for carbon-11 labeled radiopharmaceuticals has triggered technological advances in fields of radiochemistry and automated modules. Even though carbon-11 has a short half-life ($t_{1/2}=20.4min$), the consecutive second production of carbon-11 labeled radiopharmaceutical in one $^{11}C$-synthetic module should be delayed at least over 4 h to avoid the high radiation exposure. We herein aimed to produce two different carbon-11 labeled radiopharmaceuticals ([$^{11}C$]PIB and [$^{11}C$]methionine) by sharing of [$^{11}C$]methylation source in one $^{11}C$-synthetic module. The synthesis of $^{11}C$-labeling reagents ($[^{11}C]CH_3I$ or $[^{11}C]CH_3OTf$) is fully automated using the commercial TRACERlab $FX_{C-pro}$ module and is readily adaptable to $^{11}C$-labeling reactor for [$^{11}C$]PIB as well as another $^{11}C$-labeling apparatus for [$^{11}C$]methionine via the three-way valve. After completing the [$^{11}C$]PIB production, the re-synthesized $[^{11}C]CH_3I$ was passed through the three-way valve connected the polyetheretherketone (PEEK) line and loaded into the C18 Sep-Pak cartridge including the methionine precursor. The labeled product [^${11}C$]methionine was purified by a simple cartridge separation and reformulated into saline. The radiochemical yield of [$^{11}C$]PIB and [$^{11}C$]methionine were $5.3{\pm}0.6%$ and $18.7{\pm}0.8%$ (n.d.c.), respectively, with over 97% of radiochemical purity. The specific activity of [$^{11}C$]PIB was over $110GBq/{\mu}mol$. Total production time of two radiopharmaceuticals needs about 2 h from $1^{st}$ beam irradiation including quality control tests. Final [$^{11}C$]PIB and [$^{11}C$]methionine were satisfied all quality control test standards.

• 대한치과보철학회지
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• 제57권2호
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• pp.189-194
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• 2019

심한 치조골 흡수를 동반한 편악 무치악 환자의 보철 수복시 대합치열의 상태를 고려하여 올바른 교합평면을 설정하고, 교합력이 균일하게 분산될 수 있는 치료가 제공되어야 한다. 임플란트 유지 피개의치는 소수의 임플란트로 치조골 흡수가 심한 완전 무치악 환자에게 총의치보다 우수한 유지와 안정성을 주는 치료이다. 최근 치과 영역에서 소개된 신소재 polyaryletherketone (PAEK) 기반의 폴리머(Pekkton ivory, Cendres + $M{\acute{e}}taux$ SA, Biel / Bienne, Switzerland)를 사용한 telescopic 어태치먼트는 전형적인 telescopic 코핑의 이점을 가지며, 내마모성이 뛰어나며, 기존의 임플란트 피개의치에 비해 가볍고 경제적인 장점이 있다. 본 증례에서는 상악 완전 무치악 환자에 임플란트를 5개 식립하여, Pekkton으로 내 외관이 제작된 텔레스코픽 어태치먼트를 활용한 임플란트 유지 피개의치를 제작하고, 하악은 임플란트 고정성 보철로 수복하였다. 심미적 및 기능적으로 만족스러운 결과를 얻었기에 이를 보고하는 바이다.

• Journal of Korean Neurosurgical Society
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• 제65권1호
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• pp.96-106
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• 2022

Objective : The most common complication of anterior cervical discectomy and fusion (ACDF) is cage subsidence and maintenance of disc height affects postoperative clinical outcomes. We considered cage subsidence as an inappropriate indicator for evaluating preservation of disc height. Thus, this study aimed to consider patients with complications such as reduced total disc height compared to that before surgery and evaluate the relevance of several factors before ACDF. Methods : We retrospectively reviewed the medical records of 40 patients who underwent stand-alone single-level ACDF using a polyetheretherketone (PEEK) cage at our institution between January 2012 and December 2018. Our study population comprised 19 male and 21 female patients aged 24-70 years. The minimum follow-up period was 1 year. Twenty-seven patients had preoperative bone mineral density (BMD) data on dual-energy X-ray absorptiometry. Clinical parameters included sex, age, body mass index, smoking history, and prior medical history. Radiologic parameters included the C2-7 cobb angle, segmental angle, sagittal vertical axis, disc height, and total intervertebral height (TIH) at the preoperative and postoperative periods. Cage decrement was defined as the reduction in TIH at the 6-month follow-up compared to preoperative TIH. To evaluate the bone quality, Hounsfield unit (HU) value was calculated in the axial and sagittal images of conventional computed tomography. Results : Lumbar BMD values and cervical HU values were significantly correlated (r=0.733, p<0.001). We divided the patients into two groups based on cage decrement, and 47.5% of the total patients were regarded as cage decrement. There were statistically significant differences in the parameters of measuring the HU value of the vertebra and intraoperative distraction between the two groups. Using these identified factors, we performed a receiver operating characteristic (ROC) curve analysis. Based on the ROC curve, the cut-off point was 530 at the HU value of the upper cortical and cancellous vertebrae (p=0.014; area under the curve [AUC], 0.727; sensitivity, 94.7%; specificity, 42.9%) and 22.41 at intraoperative distraction (p=0.017; AUC, 0.722; sensitivity, 85.7%; specificity, 57.9%). Using this value, we converted these parameters into a bifurcated variable and assessed the multinomial regression analysis to evaluate the risk factors for cage decrement in ACDF. Intraoperative distraction and HU value of the upper vertebral body were independent factors of postoperative subsidence. Conclusion : Insufficient intraoperative distraction and low HU value showed a strong relationship with postoperative intervertebral height reduction following single stand-alone PEEK cage ACDF.