• 공업화학
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• 제31권4호
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• pp.411-415
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• 2020

이 논문에서는, 주요한 목질 소재의 하나인 리그닌(lignin)의 표면에 전도성고분자를 코팅한 복합체를 제조하고 이를 하이드로젤(hydrogel)에 도입하여 센서(sensor) 소재로의 활용 가능성을 검증하는 연구를 다루고자 한다. 리그닌 표면에 전도성 고분자인 폴리피롤(polypyrrole)을 중합한 후 성공적인 도입 여부는 적외선(FT-IR) 분광기를 통하여 확인하였고 그 형태는 주사전자현미경을 통하여 분석하였다. 얻어진 폴리피롤@리그닌(PPy@lignin) 복합 소재는 하이드로젤과 혼합하여 전도성을 띄는 하이드로젤을 형성하였다. 이어서, 전기적 측정을 통하여 전도성 여부를 검증하였다. 이 하이드로젤이 센서 소재로 활용될 수 있는지 확인하기 위하여, 여러 가지 용매류 및 용액류를 하이드로젤에 도입하여 센서 신호를 얻었고, 그 유효성 여부를 다양한 보완실험과 교차검증을 통하여 확인하였다. 향후 다양한 후속 연구가 필요하겠지만, 현 연구에서는 폴리피롤@리그닌 복합재를 포함한 하이드로젤이 센서 소재로 활용될 가능성이 충분함을 알 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.204-204
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• 1999

The plasma source ion implantation(PSII) technique which is a method using high negative voltage pulse in plasma system has the potential to change the surface properties of polymer. PSII technique increase the surface free energy by introducing polar functional groups on the surface so that it improves reactivity, hydrophilicity, adhension, biocompatability, etc. However, the mobility of polymer chains enables the modified surface layers to adapt their composition to interfacial force. This hydrophobic recovery interrupts the stability of modified surfaces to keep for the long time. In this study, poly(methyl methacrylate)(PMMA), poly(2-hydroxyethyl methacrylate)(PHEMA), and polu(2-hydroxypropyl methacylate)(PHPMA) for contact lens application, were modified to improve the wettability with PSII technique and were investigated the surface stabilities. Polymer film was prepared with solution casting(3 wt.% solution) and was annealed at 11$0^{\circ}C$ under vacuum oven to remove solvent completely and to eliminate physical ageing. The thickness of the film measured by scanning electron microscopy (SEM) and surface profilometer was about 10${\mu}{\textrm}{m}$. Polymers were treated with different kinds of gases, pulse frequency, pulse with, pulse voltage, and treatment time. Even though PMMA, PHEMA, and PHPMA have similar repeat unit structure, the optimal treatment conditions and the tendency to hydrophobic recovery were different. PHPMA, more hydrophilic polymer than PMMA and PHEMA showd better wettability and stability after mild treatment. Surface tensions were obtained by water and diiodomethane contact angle measurements to monitor the relation between hydrophobic recovery and polymer structure. Different ion species in plasma change the polar component and dispersion component of polymer surface. For better wettability surface, the increase of polar component was a dominant factor. We also characterized modified polymer surfaces using x-ray photoelectron spectroscopy(XPS), secondary ion mass spectrometry(SIMS), Fourier Transform infrared spectroscopy(FT-IR), and SEM.

• 한국세라믹학회지
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• 제46권6호
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• pp.574-582
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• 2009

$UO_2$ microsphere particles, core material of HTGR(High Temperature Gas Reactor) nuclear fuel, were prepared using by the GSP(Gel Supported Precipitation) method which is a modified-method of the wet sol-gel process. The spherical shape of initial liquid ADU droplets from the vibration nozzle system was continuously kept till the conversion to the final $UO_2$ microsphere. But the size of a final $UO_2$ microsphere was shrunken to about 25% of an initial ADU droplet size. Also, we found that the composition of dried-ADU gel particles was constituted of the very complicated phases, coexisted the U=O, C-H, N-H, N-O, and O-H functional groups by FT-IR. The important factors for obtain the no-crack $UO_2$ microsphere during the thermal treatment processes must perfectly wash out the remained-$NH_4NO_3$ within the ADU gel particle in washing process and the selections of an appropriate heating rate at a suitable gas atmosphere, during the calcining of ADU gel particles, the reducing of $UO_3$ particles, and the sintering of $UO_2$ particles, respectively.

• 한국수소및신에너지학회논문집
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• 제26권4호
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• pp.324-330
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• 2015

The electrolyte flow rates of vanadium redox flow battery play very important role in terms of ion transfer to electrolyte, kinetics and pump efficiency in system. In this paper a vanadium redox flow battery single cell was tested to suggest the optimization criteria of electrolyte flow rates on the efficiencies. The compared electrolyte circulation flow rates in this experimental work were 15, 30 and 45 mL/min. The charge/discharge characteristics of the flow rate of 30 mL/min was the best out of all flow rates in terms of charging and discharging time. The current efficiencies, voltage efficiencies and energy efficiencies at the flow rate of 30 mL/min were the best. The IR losses obtained at thd current density of $40mA/cm^2$, at the flow rates of 15, 30 and 45 mL/min were 0.085 V, 0.042 V and 0.115 V, respectively. The charge efficiencies at the current density of $40mA/cm^2$ were 96.42%, 96.45% and 96.29% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. The voltge efficiencies at the current density of $40mA/cm^2$ were 77.34%, 80.62% and 76.10% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. Finally, the energy efficiencies at the current density of $40mA/cm^2$ were 74.57%, 77.76% and 73.27% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. The optimum flow rates of electrolytes were 20 mL/min in most of operating variables of vanadium redox flow battery.

• 한국산학기술학회논문지
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• 제6권2호
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• pp.195-201
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• 2005

본 논문에서는 새로운 실시간 시선 추적 방식을 제안하고자한다. 기존의 시선추적 방식은 사용자가 머리를 조금만 움직여도 잘못된 결과를 얻을 수가 있었고 각각의 사용자에 대하여 교정 과정을 수행할 필요가 있었다. 따라서 제안된 시선 추적 방법은 적외선 조명과 Generalized Regression Neural Networks(GRNN)를 이용함으로써 교정 과정 없이 머리의 움직임이 큰 경우에도 견실하고 정확한 시선 추적을 가능하도록 하였다. GRNN을 사용함으로써 매핑기능은 원활하게 할 수 있었고, 머리의 움직임은 시선 매핑 기능에 의해 적절하게 시선추적에 반영되어 얼굴의 움직임이 있는 경우에도 시선추적이 가능토록 하였고, 매핑 기능을 일반화함으로써 각각의 교정과정을 생략 할 수 있게 하여 학습에 참여하지 않은 다른 사용자도 시선 추적을 가능케 하였다. 실험결과 얼굴의 움직임이 있는 경우에는 평균 90%, 다른 사용자에 대해서는 평균 85%의 시선 추적 결과를 나타내었다.

• 정보처리학회논문지B
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• 제16B권3호
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• pp.203-214
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• 2009

본 연구에서는 모니터, 카메라 및 눈동자 좌표계간의 복잡한 3차원 관계를 고려하지 않고, 동공의 중심 위치와 모니터의 구석에 설치된 적외선 조명에 의한 네 개의 조명 반사광 사이의 관계를 사용하여 2차원적인 변환 방법으로 사용자의 시선 위치를 파악한다. 동공중심과 조명 반사광을 정확하게 추출하고, 이를 통해 계산된 시선 위치 계산의 정확도에 영향을 줄 수 있는 오차 요소들을 보정하는 것이 본 연구의 목적이다. 이를 위하여, 동공 중심을 통해 계산된 시선위치와 실제 시선 축이 이루는 카파에러를 초기 1회의 사용자 캘리브레이션을 통해 보정하였다. 또한, 칼만 필터를 기반으로 눈의 급격한 움직임 변화에도 각막 조명 반사광을 안정적으로 추적하여 시선 위치를 정확하게 추적한다. 실험 결과, 제안한 연구방법의 시선 위치 추출 오차는 눈의 급격한 움직임 변화에 상관없이 약 1.0$^\circ$ 를 나타냈다.

• 한국표면공학회지
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• 제46권4호
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• pp.139-144
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• 2013

c-BN(cubic boron nitride) is known to have extremely high hardness next to diamond, as well as very high thermal and chemical stability. The c-BN in the form of film is useful for wear resistant coatings where the application of diamond film is restricted. However, there is less practical application because of difficult control of processing variables for synthesis of c-BN film as well as unclear mechanism on formation of c-BN. Therefore, in the present study, the structural characterization of c-BN thin film were investigated using $B_4C$ target in r.f. magnetron sputtering system as a function of processing variables. c-BN films were coated on Si(100) substrate using $B_4C$ (99.5% purity). The mixture of nitrogen and argon was used for carrier gas. The deposition processing conditions were changed with substrate bias voltage, substrate temperature and base pressure. Fourier transform infrared microscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were used to analyze crystal structures and chemical binding energy of the films. In the case of the BN film deposited at room temperature, c-BN was formed in the substrate bias voltage range of -400 V~ -600 V. Less c-BN fraction was observed as deposition temperature increased and more c-BN fraction was observed as base pressure increased.

• 한국수산과학회지
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• 제20권4호
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• pp.273-281
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• 1987

In this work the antioxidant effects of browning reaction products prepared by xylose-tryrtophan reaction system were discussed. The antioxygenic brown pigments were separated by solvent extraction, and column chromatography and isolated by gel filteration. The functional groups of the brown pigments which had antioxidant activity were examined. The brown pigments extracted with methanol showed antioxidant effect and were fractionated in 5portions on DEAE-cellulose column. The elutes with methanol: acetic acid(10:30 v/v sol n(A), methanol: chloroform(95:5 v/v) sol n(C), and chloroform: acetic acid(10:30 v/v) sol n(E) only showed antioxidant activity and their compositions were 22.43, 21.51 and $34.43\%$ respectively. When each fraction on DEAE-cellulose column was reseparated on Sephadex LH-20 column, 2 fractions were obtained from portion A and C respectively. Molecular weights of A, C and E fraction of brown pigments were from 2,600 to 3,700. By elucidation of IR spectra, the pigment fractions which showed a strong antioxidant activity were tearing the indole group. It is suggested that the antioxidant function of the brown pigment is due to hydroxy and amino group. A higher activity of the brown pigment fraction E might be attributed to carboxylic acid or carboxylic ester compounds.

• Tribology and Lubricants
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• 제32권5호
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• pp.141-146
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• 2016

The diketopyrrolopyrrole (DPP) pigment is a bicyclic 8-π-electron system containing two lactam units. Typical DPP derivative pigments have melting points of over 350°C and very low solubility in most solvents, and show absorption in the visible region with a molar extinction coefficient of 33,000 dm²mol⁻¹ and strong photoluminescence with maxima in the range 500–600 nm. X-ray structure analyses of DPP show that the whole molecule is almost in one plane. The phenyl rings are twisted out of the heterocyclic plane and the intermolecular hydrogen bonding between neighboring lactam NH and carbonyl units influences the structure of the DPP pigment in the solid state. In this study, mono-N-alkylation and mono-N-arylation were undertaken for Pigment Red 264 or Pigment Orange 73 with alkyl halide and aryl halide, respectively, in the presence of sodium tert-butoxide as a base catalyst to improve the solubility of DPP pigments and their application as CO₂ indicators. The synthetic yield was in the range 11–88%. The indicator dyes are highly soluble in organic solvents and shows pH-dependent absorption (λ_max 501 and 572 nm for the protonated and deprotonated forms, respectively) and emission (λ_max 524 and 605 nm for the protonated and deprotonated forms, respectively) spectra. The mono-N-alkylated and mono-N-arylated DPP pigment was identified by ¹H-NMR (¹H-Nuclear Magnetic Resonance Spectrometer), FT-IR (Fourier Transform Infrared Spectroscopy), and MS (Mass Spectrometry). According to the results of color and hue properties obtained by a color matching analyzer, the synthesized DPP pigment material can be used as a CO₂ indicator.

• Korean Journal of Acupuncture
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• 제20권2호
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• pp.1-20
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• 2003

This study was examined for characteristics of acupuncture of LU10 on the abdominal thermography of health subject. The volunteers who participating in this study had taken rest for 20 - 30 mins in room temperature $(23-25^{\circ}C)$ before the examination and informed them what to prohibit smoking, drinking and administration of drug for the previous day. The thermography of abdomen including a below part of the chest was taken using Infra-Red Imaging System (IR 2000, MEDI-CORE Co., Korea) by time interval of 15 minutes at 15 min before, just before and 15 min after, 30 min after and 45 min after acupuncture stimulation. Acupuncture was applied to both LU10 for 30 mins. The results showed that acupuncture of LU10 for 30 mins had more potencies of changes on all the ROIs of abdominal thermography than those of control group. Also, those responses were significantly clear at the A1, A3, A6, A7 and A9 areas. It was observed that the quantities of thermal changes following acupuncture of LU10 been increased significantly comparing that of control group at the all ROIs (region of interest). These effects have more potencies at the upper (A1 and A2) and below (A7, A8, A9) abdominal areas than midline ones (A4, A5, and A6). These results suggest that acupuncture of LU10 having the characteristics of controls of chill and fever (寒熱) may modulate thermal distributions and changes of abdominal areas including the below of chest.