• 제목/요약/키워드: Oh Gyu-won

검색결과 292건 처리시간 0.028초

홑겹 탄소 나노튜브 네트워크의 게이트 의존성과 온도 의존성 (Field effect and temperature dependence on the conductance of the carbon nanotube network)

  • 오동진;원부운;김강현;강해용;김혜영;김규태
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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    • pp.147-150
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    • 2004
  • Back gate가 있는 $SiO_2$ 기판에 SWCNT(Single Walled Carbon Nanotube) 분산액을 도포하여 SWCNT 네트워크를 형성하였다. 금선을 shadow mask로 사용하여 $10{\mu}m$ 간격의 2단자 금 전극을 열 증착을 통해 형성하였다. 현미경 포토리소그래피를 통하여 시료의 가장자리를 Photoresist로 남겨두어 시료 가장자리의 나노튜브를 통한 단락을 방지하였다. 전류-전압 특성, 게이트 특성과 온도 의존성은 DAQ(Data Aquisition) 보드와 Keithley 2400을 사용하여 측정하였고, Labview 기반 프로그램을 통해 제어하였다. 음의 게이트 전압에서의 저항 감소를 관측함으로써 네트워크 상태에서의 게이트 의존성이 P 형 반도체 성질을 보여줌을 알 수 있었으며, 온도가 올라감에 따라 저항이 지수 함수적으로 증가하는 것으로부터 네트워크의 온도 의존성이 금속성 온도 의존성을 가지는 것을 확인하였다.

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Synthesis of Spherical Carbons Containing Titania and Their Physicochemical and Photochemical Properties

  • Oh, Won-Chun;Kim, Jong-Gyu;Kim, Hyuk;Chen, Ming-Liang;Zhang, Feng-Jun;Meng, Ze-Da;Choi, Jong-Geun;Zhang, Kan
    • 한국세라믹학회지
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    • 제48권1호
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    • pp.6-13
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    • 2011
  • In this study, we used activated carbon (AC) and charcoal (CH) as carbon sources with $TiO_2$ powder to prepare spherical carbons containing titania (SCCT) by using phenolic resin (PR) as a bonding agent. The physicochemical characteristics of the SCCT samples were examined by BET, XRD, SEM, EDX, iodine adsorption and compressive strength. The photocatalytic activity was evaluated by measuring the removal efficiency of three kinds of organic dyes: methylene blue (MB), methyl orange (MO) and rhodamine B (Rh.B) under a UV/SCCT system. In addition, evaluation of chemical oxygen demand (COD) of piggery waste was done at regular intervals and gave a good idea about the mineralization of wastewater.

PVD방식을 이용한 NDLC 박막에서의 액정 배향 효과 (Liquid Crystal orientation on the NDLC Thin Film Deposited using physical deposition method)

  • 이원규;오병윤;임지훈;나현재;이강민;박홍규;서대식
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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    • pp.301-301
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    • 2008
  • Ion beam (IB)-induced alignment of inorganic materials has been investigated intensively as it provides controllability in a nonstop process for producing high-resolution displays[1][2]. LC orientation via ion-beam (IB) irradiation on the nitrogen doped diamond like carbon (NDLC) thin film deposited by physical deposition method-sputtering was embodied. The NDLC thin film that was deposited by sputter showed uniform LC alignment at the 1200eV of the ion beam intensity. The pretilt angle of LC on NDLC thin films was measured with various IB exposure time and angle. The maximum pretilt angle were showed with IB irradiation angle of $45^{\circ}$ and exposure time of 62.5 sec, respectively. To show NDLC thin film stability in high temperature, thermal stability test was proceeded. The uppermost of the thermal stability of NDLC thin film was $200^{\circ}C$. In this investigation, the electro-optical (EO) characteristics of LC on NDLC thin film were measured.

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Baicalein Protects Human Skin Cells against Ultraviolet B-Induced Oxidative Stress

  • Oh, Min Chang;Piao, Mei Jing;Jayatissa Fernando, Pattage Madushan Dilhara;Han, Xia;Madduma Hewage, Susara Ruwan Kumara;Park, Jeong Eon;Ko, Mi Sung;Jung, Uhee;Kim, In Gyu;Hyun, Jin Won
    • Biomolecules & Therapeutics
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    • 제24권6호
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    • pp.616-622
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    • 2016
  • Baicalein (5,6,7-trihydroxy-2-phenyl-chromen-4-one) is a flavone, a type of flavonoid, originally isolated from the roots of Scutellaria baicalensis. This study evaluated the protective effects of baicalein against oxidative damage-mediated apoptosis induced by ultraviolet B (UVB) radiation in a human keratinocyte cell line (HaCaT). Baicalein absorbed light within the wavelength range of UVB. In addition, baicalein decreased the level of intracellular reactive oxygen species (ROS) in response to UVB radiation. Baicalein protected cells against UVB radiation-induced DNA breaks, 8-isoprostane generation and protein modification in HaCaT cells. Furthermore, baicalein suppressed the apoptotic cell death by UVB radiation. These findings suggest that baicalein protected HaCaT cells against UVB radiation-induced cell damage and apoptosis by absorbing UVB radiation and scavenging ROS.

측두하악관절 수술 후 관절 운동프로그램이 기능회복에 미치는 영향 (Effect of a Therapeutic Exercise Program on the Functional Recovery Following Temporomandibular Joint Surgery)

  • 오덕원;김기송;이규완;정낙수
    • 한국전문물리치료학회지
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    • 제6권3호
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    • pp.94-109
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    • 1999
  • The purposes of this study were to assess the effect of therapeutic exercise and to offer an approach to the physical therapy and rehabilitation procedure of the temporomandibular joint (TMJ) following surgery. In this research, 42 patients with TMJ surgery were assigned one of two groups. The experimental group included 21 patients who performed therapeutic exercise, and the control group included 21 patients who did not perform therapeutic exercise. Conservative therapy such as an ice pack, a hot pack, and pulsed ultrasound was applied to both groups. Treatment was applied twice a day during the admission period and, after discharge, everyday for six weeks. Visual analogue scale (VAS), incisal biting force, and joint ROM were measured before surgery and at 30 days after surgery. The results were as follows: VAS (p<0.05), mouth opening (p<0.01), lateral excursion to unaffected side (p<0.05), and protrusion (p<0.05) between experimental group and control group showed statistically significant differences. Incisal biting force and lateral excursion to affected side between experimental group and control group showed no statistically significant difference.

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Preparation of Spherical Activated Carbon and Their Physicochemical Properties

  • Oh, Won-Chun;Kim, Jong-Gyu;Kim, Hyuk;Chen, Ming-Liang;Zhang, Feng-Jun;Zhang, Kan;Meng, Ze-Da
    • 한국세라믹학회지
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    • 제46권6호
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    • pp.568-573
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    • 2009
  • In this study, we used coal based activated carbons as starting material and phenolic resin (PR) as a bonding agent to prepare spherical shaped activated carbons. The textural properties of SAC were characterized by BET surface area, XRD, SEM, iodine adsorption, strength intensity and pressure drop. According to the results, the spherical activated carbon prepared with activated carbon and PR at a ratio of 60:40 was found to have the best formation of spherical shape, which was found in sample SAC40. After activation, SAC40 has high BET surface area, iodine adsorption capability and strength value, and lowest pressure drop.

두 파라메타 탄성기초위에 놓인 불균일 Timoshenko보의 안정성과 진동 (Stability and Vibration of Non-Uniform Timoshenko Beams resting on Two-Parameter Elastic Foundations)

  • 이종원;류봉조;이규섭;공용식;오부진
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 춘계학술대회논문집A
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    • pp.596-601
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    • 2000
  • The paper presents free vibration and stability analyses of a non-uniform Timoshenko beam resting on a two-parameter elastic soil. The soil parameters can vary along the spat and is assumed to be two-parameter model including the effects of both transverse shear deformation and elastic foundation Governing equations related to the vibration and the stability of the beam are derived from Hamilton's principle, and the resulting eigen-value problems can be solved to give natural frequencies and critical force by finite element method. Numerical results for both vibration and stability of beams under an axial force are presented and compared with other available solutions. Finally, vibration frequencies, mode shapes and critical forces are investigated for various thickness ratios, shear foundation parameter, Winkler foundation parameter and boundary conditions of tapered Timoshenko beams.

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심프슨 근사법을 이용한 MTF 그래프 작성에 관한 연구 (A Study on the MTF Graphics using Simpson Approximation)

  • 최규식;장원석;오재익
    • 한국항행학회논문지
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    • 제16권2호
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    • pp.401-408
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    • 2012
  • 측정, 통신, 광정보전달학 등의 분야에서 광 장치를 이용한 광소자의 역할이 점점 증대됨에 따라 이들을 특징 지을 명확한 근거가 필요하게 되었다. 특히 영상시스템에서 이러한 필요를 만족시켜줄 아주 기본적이고도 극히 중요한 측정 파라미터로서 MTF가 있다. 지난 수십년에 걸쳐서 레이저 간섭계, CCD카메라, 컴퓨터를 포함한 새로운 기기들이 등장하여 MTF를 측정하고 계산하는 데에 획기적인 변화를 초래하였다. 그런데 이 MTF를 계산하려면 지루하고도 더딘 과정을 거쳐야 한다. 따라서 우리는 여기서 심프슨 근사법을 이용하여 MTF를 간단히 계산하고 그래프로 구현할 수 있는 방법을 제시하였다. 이 방법은 근사법이긴 하나 정밀값과의 오차가 극히 적어서 실현하기에 매우 유익한 기법이다.

정신분열병과 Catechol-O-methyltransferase(COMT) 유전자 다형성의 연합 (An Association Study of COMT Gene Polymorphism with Korean Schizophrenics)

  • 송은숙;양병환;박강규;이유상;안은숙;오동열;김종원;최인근;김길숙;채영규
    • 생물정신의학
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    • 제5권2호
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    • pp.210-214
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    • 1998
  • An association study with Korean schizophrenic patients(N=84) and normal controls(N=87) was performed to find the relationship between catechol-O-methyltransferase(COMT) gene polymorphism and schizophrenia using polymerase chain reaction-restriction fragment length polymorphism. When we compared the allele and genotype frequencies of Bgl I COMT gene polymorphism in schizophrenics and normal controls, there was no significant difference between two groups. Our results do not support an association between the Bgl I polymorphism of COMT gene and schizophrenia.

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고량강 추출물로부터 분리된 Flavonoid 화합물의 혈압강하 효과 (Vasorelaxation Effect of the Flavonoids from the Rhizome Extract of Alpinia offcinarum on Isolated Rat Thoracic Aorta)

  • 김혜진;유미영;김현기;이병호;오광석;서호원;연규환;;권대영;김영섭;유시용
    • 생약학회지
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    • 제37권1호통권144호
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    • pp.56-59
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    • 2006
  • The vascular relaxant effets of Alpinia officinarum(Zingiberaceae) were evaluated on isolated thoracic aorta from rats. The methanolic extract of rhizome of Alpinia officinarum caused a concentration-dependent relaxation of rat aortic preparations precontracted with $0.3{\mu}M$ phenylephrine, The intensive investigation of the extract by way of activity-guided fractionation led us to yield three kind of active components, galangin(1), kaempferide(2), and kaempferol(3), which were responsible for the vasodilating property of the extract. Stuctures of the isolated active components were established by chemical and spectroscopic means.