• 대한치과보철학회지
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• 제39권3호
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• pp.273-281
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• 2001

Digital subtraction radiography may be one of the most precise and noninvasive methods for assessing subtle density changes in peri-implant bone, providing additional diagnostic information on implant tissue integration in overall maintenance. The aims of this study were to evaluate density changes after first, second surgery of dental implant and to measure the amount of marginal bone loss 9 months after second surgery using digital subtraction radiography. Bone change around 30 screw-shaped implants in 16 patients were assessed on radiographs. 17 Branemark implants of 3.75mm in diameter(Nobel Biocare, Goteborg, Sweden), 2 Branemark implants of 5.0mm in diameter, 11 $Replace^{TM}$ implants of 4.3mm in diameter(Nobel Biocare, Goteborg, Sweden) were used. To standardize the projection geometry of serial radiographs of implants, customized bite block was fabricated using XCP film holder(Rinn Corporation, Elgin, IL.) with polyether impression material of Impregum(ESPE, Germany) and direct digital image was obtained. Qualitative and quantitative changes on radiographs were measured with Emago software(The Oral Diagnostic System, Amsterdam, Netherlands). The results were as follows: 1. The peri-implant bone density of 69.2% implants did not change and the peri-implant bone density of 30.8% implants decreased after 3 months following first surgery. 2. The crestal bone density of 53.9% implants decreased first 3 months after second surgery. The crestal bone density of 58.8% implants increased 9 months after second surgery. No density change was observed around the midportion of the implants after second surgery, 3. The amount of marginal bone loss between different kinds of implants showed no statistically significant differences (p>0.05). 4. More than 90% of total marginal bone loss recorded in a 9-month period occurred during the first 3 months.

• Elastomers and Composites
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• 제44권3호
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• pp.274-281
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• 2009

음이온중합기구으로 나이론 6와 나이론공중합체를 합성하였다. 나이론탄성체는 카프록락탐과 이소시아네이트로 활성화된 폴리올을 음이온중합기구을 통해서 공중합을 하였다. 전기방사공정으로 제조된 나이론과 나이론공중합체는, FE-SEM으로 구조를 분석한 결과, 100$\sim$180 nm의 직경을 갖는 나노섬유들로 이루어진 다공성 부직포였다. DSC와 ATR FT-IR을 이용하여 결정화거동 및 구조를 분석하였다. 인장실험을 한 결과 나이론은 나이론탄성체에 비해서 인장강도는 크고, 신율은 감소된다. 결정영역인 PA블록과 무정형인 PE블록으로 된 나이론공중합체인 나이론 탄성체는 PE블록 비율이 클수록 인장강도는 낮아지고 신율은 증가된다. $O_2$와 $N_2$를 반응기체로 한 상압플라즈마로 전기방사된 나이론과 나이론탄성체의 부직포표면을 개질한 결과, 개질된 부직포표면은 표면개질 전보다 더 친수성을 보였으며 반면에 $CH_4$를 반응기체로 사용한 상압플라즈마로는 부직포표면을 개질하면 부직표면은 소수성을 나타내었다.

• Journal of Information Display
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• 제7권3호
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• pp.13-18
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• 2006

Currently, the flexible organic light emitting devices (OLEDs) are investigated. They are very vulnerable to moisture, and thus have been found to show some problems. Thus, an effective barrier layer is needed to protect from moisture in air. We deposited thin films with magnesium oxide (MgO) and silicon oxide $(SiO_{2})$ compounds mixed at various mixture ratios on flexible polyether sulfone (PES) substrates by an electron-beam evaporator to investigate their applizability for transparent barrier applications. In this study, we found that as the MgO fraction increased, thin films comprised of MgO and $(SiO_{2})$ compounds became more amorphous and their surface morphologies become smoother and denser. In addition, zirconium oxide $(ZrO_{2})$ was added to the above-mentioned compound mixtures. $ZrO_{2}$ made thin mixture films more amorphous and made the surface morphology denser and more uniform. The water vapor transmission rates (WVTRs) of the whole films decreased rapidly. The best WVTR was obtained by depositing thin films of Mg-Si-Zr-O compound among the whole thin films. As the thin mixture films became more amorphous, and the surface morphology become denser and more uniform, the WVTRs decreased. Therefore, the thin mixture films became more suitable for flexible OLED applications as transparent passivation layers against moisture in air.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.371-372
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• 2005

Supercapacitors are promising devices for delivering high power density. Digital communications, electric vehicles and other devices that require electrical energy at high power levels in relatively short pulses have prompted considerable research on supercapacitors. In recent years, solid electrolytes have been investigated for supercapacitors. Solid electrolytes are advantageous over liquid electrolytes in respect of easy handling and reliability without electrolyte leakage. In this preliminary study, an electrochemical supercapacitor in all solid configuration has been fabricated using CNF-DAAQ and poly-vinylidenefluoride(PVdF). A new type of Supercapacitor was constructed by using carbon nanofibers(CNFs) and DAAQ(l,5-diaminoanthraquinone) monomer. DAAQ was deposited on the carbon nanofibers by chemical polymerization with $(NH_4)_2S_2O_8$ as oxidant in the 0.1M $H_2SO_4$. Dried SPEEK powder was mixed with N-methyl pyrrolidone to make 10 wt.% solution in an ultrasonic bath, the slurry was cast over a glass substrate heated to $70^{\circ}C$ for solvent evaporation. And then we used solid electrolyte of SPEEK. The unit cell consist of DAAQ-CNF/electrolyte/Pt. From the analysis, it is clear that surface of carbon nanofibers was quite uniformly coated with DAAQ. The performance characteristics of the supercapacitors have been evaluated using Cyclic Voltammetry.

• Journal of Korean Neurosurgical Society
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• 제60권5호
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• pp.567-576
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• 2017

Objective : Preoperative parameters including the T1 slope (T1S) and C2-C7 sagittal vertical axis (SVA) have been recognized as predictors of kyphosis after laminoplasty, which is accompanied by posterior neck muscle damage. The importance of preoperative parameters has been under-estimated in anterior cervical discectomy and fusion (ACDF) because there is no posterior neck muscle damage. We aimed to determine whether postoperative subsidence and pseudarthrosis could be predicted according to specific parameters on preoperative plain radiographs. Methods : We retrospectively analyzed 41 consecutive patients (male : female, 22 : 19; mean age, $51.15{\pm}9.25years$) who underwent ACDF with a stand-alone polyether-ether-ketone (PEEK) cage (>1 year follow-up). Parameters including SVA, T1S, segmental angle and range of motion (ROM), C2-C7 cervical angle and ROM, and segmental inter-spinous distance were measured on preoperative plain radiographs. Risk factors of subsidence and pseudarthrosis were determined using multivariate logistic regression. Results : Fifty-five segments (27 single-segment and 14 two-segment fusions) were included. The subsidence and pseudarthrosis rates based on the number of segments were 36.4% and 29.1%, respectively. Demographic data and fusion level were unrelated to subsidence. A greater T1S was associated with a lower risk of subsidence (p=0.017, odds ratio=0.206). A cutoff value of T1S<$28^{\circ}$ significantly predicted subsidence (sensitivity : 70%, specificity : 68.6%). There were no preoperative predictors of pseudarthrosis except old age. Conclusion : A lower T1S (T1S<$28^{\circ}$) could be a risk factor of subsidence following ACDF. Surgeons need to be aware of this risk factor and should consider various supportive procedures to reduce the subsidence rates for such cases.

• 한국응용과학기술학회지
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• 제36권2호
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• pp.524-530
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• 2019

본 연구에서는 가죽 스킨층에 코팅용으로 사용할 수용성 폴리우레탄의 합성을 위해 polyrupopylene mono methyl ether (PM)를 기반으로 폴리 에테르 폴리올인 폴리 프로필렌 글리콜과 이소포론 디 이소시아네이트 (isophorone diisocyanate, IPDI)를 합성 하였다. 예비 중합체의 합성 후, 점도 상승을 억제하기 위해 $40^{\circ}C$에서 1M, 2M, 3M 및 4M으로 PM을 첨가하고 중화 반응 및 사슬연장 반응을 수행하여 폴리 우레탄 시료를 준비 하였다. 준비된 시료의 인장강도와 연신율, 접착강도를 측정한 결과로 인장강도는 PM 이 1M 일 때 2.109 kgf/mm2, 4M 에서 1.721kgf/mm2, 연신율은 PM이 1M일 때 496%, 4M 에서 522%, 접착력은 PM이 1M 일 때 1.114 kgf/cm, 4M 에서 0.99 kgf/cm 로 확인 되었다.

• Tribology and Lubricants
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• 제35권2호
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• pp.87-93
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• 2019

This work aims to develop a dry lubricant for oilless bush, especially a solid lubricant, thereby creating a coating method with improved properties of anti-friction and load-carrying capacity without oil lubrication. In this work, spherical-shaped powders of thermosetting resin such as polyimide (PI) are mixed with a binder matrix obtained by mixing a fluorocarbon compound resin such as Polytetrafluoroethylene (PTFE) or Ethylene tetra fluoro ethylene (ETFE) with itself or with a non-fluorocarbon thermoplastic resin such as Polyether ether ketone (PEEK). And these dry lubricant mixtures are thickly coated (200-300 mm in the thickness) on the inner surface of the bush by using a wet-typed air-spray deposition method. It was found that the load-carrying capacity of the solid lubricant for excavator bush (60 mm in diameter) that operates under a high load condition (at 40 MPa) is greatly improved owing to the spherical-shaped powders of thermosetting resin. In addition, the coefficient of friction at the sliding surface is also reduced less than 0.1. Thick coating also lowers the contact stress at the edge of a bush that results in better tribological performances. The result suggests that the lubrication performance and durability life of the bush can be remarkably improved even without lubrication (oil or grease).

• 한국군사과학기술학회지
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• 제25권4호
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• pp.434-442
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• 2022

Highly toxic chemical warfare agents(CWA) could be used in chemical warfare and terrorism. The protection of skin is crucial for civilians and soldiers, because the primary routes of exposure to CWA are inhalation and skin absorption. Thus, topical skin protectants(TSP) have been studied and developed in many countries to complement protective equipments. In this study, in-vitro test procedure was optimized and established using a flow-through diffusion cell system containing excised hairless mouse skin in an attempt to assess the effectiveness of various TSP formulations against nerve agent simulants. In addition, the test results on the formulations including the ingredients used in SERPACWA(Skin Exposure Reduction Paste Against Chemical Warfare Agent) and IB-1(TSP of Israel) were included, indicating that the formulations with perfluorinated compounds were more effective than the glycerin-based formulations.

• 멤브레인
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• 제32권1호
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• pp.13-22
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• 2022

세계적인 에너지 수요의 증가는 통제할 수 없는 환경 오염을 야기하고 있다. 화석 연료에 대한 수요와 그로 인한 탄소 배출이 지구 온난화와 기후 변화로 이어진 것이다. 핵에너지는 청정 에너지를 생산하는 대체 자원이지만 핵연료 채굴은 유해한 화학물질과 관련이 있다. 반면에 막 분리 과정을 통해 바닷물에서 중요 광물을 채굴하는 것은 효율적이며 친환경적이다. 분리와 흡착을 통해 해수로부터 주요 광물을 채굴하는 것은 또 다른 효율적인 과정이다. 희토류 원소에서 악티늄족을 회수하는 것은 매우 어렵고 고비용의 과정이다. 압력 기반 막 분리 과정은 친환경적일 뿐만 아니라 경제적으로 실현가능한 과정이기도 하다. 본 리뷰에서 다루는 막 공정에는 폴리에테르 설폰, 폴리아미드, 폴리이미드, 폴리아미독신 및 하이브리드 막이 있다. 또한 흡착 공정의 경우, 주로 아미독심 종류의 흡착제가 논의될 것이다.

• The Korean Journal of Physiology and Pharmacology
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• 제28권1호
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• pp.21-30
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• 2024

The challenging clinical outcomes associated with advanced cervical cancer underscore the need for a novel therapeutic approach. Monensin, a polyether antibiotic, has recently emerged as a promising candidate with anti-cancer properties. In line with these ongoing efforts, our study presents compelling evidence of monensin's potent efficacy in cervical cancer. Monensin exerts a pronounced inhibitory impact on proliferation and anchorage-independent growth. Additionally, monensin significantly inhibited cervical cancer growth in vivo without causing any discernible toxicity in mice. Mechanism studies show that monensin's anti-cervical cancer activity can be attributed to its capacity to inhibit the Wnt/β-catenin pathway, rather than inducing oxidative stress. Monensin effectively reduces both the levels and activity of β-catenin, and we identify Akt, rather than CK1, as the key player involved in monensin-mediated Wnt/β-catenin inhibition. Rescue studies using Wnt activator and β-catenin-overexpressing cells confirmed that β-catenin inhibition is the mechanism of monensin's action. As expected, cervical cancer cells exhibiting heightened Wnt/β-catenin activity display increased sensitivity to monensin treatment. In conclusion, our findings provide pre-clinical evidence that supports further exploration of monensin's potential for repurposing in cervical cancer therapy, particularly for patients exhibiting aberrant Wnt/β-catenin activation.