• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.468-470
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• 2005

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of the SiC (Silicon Carbide) thin film. The SiC thin film exhibits good chemical and thermal stability. The good thermal and chemical stability makes SiC an attractive candidate for electronic applications. A vertical alignment of nematic liquid crystal by ion beam exposure on the SiC thin film surface was achieved. The about $87^{\circ}$ of stable pretilt angle was achieved at the range from $30^{\circ}$ to $45^{\circ}$ of incident angle. The good LC alignment is main-tained by the ion beam alignment method on the SiC thin film surface at high annealing temperatures up to 300.

• 한국자기학회지
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• 제25권2호
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• pp.52-57
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• 2015

텅스텐 타겟인 양극의 각도에 의존하는 X-선관 집속관의 전자빔 초점 크기를 오페라-3차원/스칼라(OPERA-3D/SCALAR) 프로그램을 이용하여 구하였다. 시뮬레이션 분석은 X-선관을 음극과 양극 그리고 4영역을 나누어 유한요소법을 적용하였다. X-선 집속관의 필라멘트로부터 방출되는 열전자 궤적은 전자밀도 분포함수에 따라 양극에 도달할 때 실초점으로 집속되고 양극에 부딪쳐서 유효 초점 크기로 X-선을 발생하게 된다. 전자빔 실초점 크기는 X-선 집속관 모양을 결정짓는 폭, 길이, 높이를 조절하여 줄일 수 있었고, 양극각도의 크기에 따라 미세하게 변하였다. 양극각도가 $10^{\circ}{\sim}17^{\circ}$에서는 전자빔 실초점 크기를 $70{\mu}m$ 이내로 유지하였고, 가장 최소 초점크기는 $15^{\circ}$에서 실초점 크기가 $40{\mu}m$로 나타났다. 최적화된 X-선 집속관의 변수들로 시뮬레이션하는 열전자의 방출 궤적을 분석하여 얻은 마이크로 크기인 실초점을 활용하는 새로운 의료 영상진단기기 개발이 가능할 것으로 보여진다.

• Earthquakes and Structures
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• 제10권6호
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• pp.1291-1314
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• 2016

The paper presents the development of experimental fragility functions for exterior RC beam-column connections based on results obtained from extensive testing carried out in the present study. Three typical types of seismically deficient beam-column connections, which are commonly prevalent in Indian sub-continent, were considered. These specimens were tested under cyclic displacement histories with different characteristics to induce different damage states. Rehabilitation specific fragility functions for damaged specimens were developed considering drift angle as a demand parameter. Four probability distributions were fit to the data and suitability of each distribution was evaluated using standard statistical method. Specimens with different damage states were rehabilitated appropriately and rehabilitated specimens were tested under similar displacement histories. Fragility functions for rehabilitated specimens have also been developed following similar procedure. Comparison of fragility functions for both original and rehabilitated specimens for each rehabilitation method showed close agreement, which establishes the effectiveness of the adopted rehabilitation strategies and hence would provide confidence in field application.

• Steel and Composite Structures
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• 제44권1호
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• pp.17-31
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• 2022

This investigation studies the characteristics of wave dispersion in sigmoid functionally graded (SFG) curved beams lying on an elastic substrate for the first time. Homogenization process was performed with the help of sigmoid function and two power laws. Moreover, various materials such as Zirconia, Alumina, Monel and Nickel steel were explored as curved beams materials. In addition, curved beams were rested on an elastic substrate which was modelled based on Winkler-Pasternak foundation. The SFG curved beams' governing equations were derived according to Euler-Bernoulli curved beam theory which is known as classic beam theory and Hamilton's principle. The resulted governing equations were solved via an analytical method. In order to validate the utilized method, the obtained outcomes were compared with other researches. Finally, the influences of various parameters, including wave number, opening angle, gradient index, Winkler coefficient and Pasternak coefficient were evaluated and indicated in the form of diagrams.

• 한국안전학회지
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• 제24권3호
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• pp.39-46
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• 2009

A recent and promising method for shear strengthening of reinforced concrete(RC) members is the use of near surface mounted(NSM) fiber reinforced polymer(FRP) reinforcement. In the NSM method, the reinforcement is embedded in grooves cut onto the surface of the member to be strengthened and filled with an appropriate binding agent such as epoxy paste or cement grout. This paper illustrates a research program on shear strengthening of RC beams with NSM channel-type FRP beams which is developed in this study. The objective of this study is to clarify the role of channel-type FRP beam embedded to the beam web for shear strengthening of reinforced concrete beams. Included in the study are effectiveness in terms of spacing and angle of channel-type FRP beams, strengthening method, and shear span ratio. the study also aims to understand the additional shear capacity due to glass fiber reinforced polymer beams and carbon reinforced polymer beams. And anther objective is to study the failure modes, shear strengthening effect on ultimate force and load deflection behavior of RC beams embedded with channel-type FRP beams on the shear region of the beams.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.136-139
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• 2003

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of a-C:H thin film as working gas at 30W rf bias condition. A high pretilt angle of about $5^{\circ}$ by ion beam(IB) exposure on the a-C:H thin film surface was measured. A good LC alignment by the IB alignment method on the a-C:H thin film surface was observed at annealing temperature of $250^{\circ}C$, and the alignment defect of the NLC was observed above annealing temperature of $300^{\circ}C$. Consequently, the high LC pretilt angle and the good thermal stability of LC alignment by the IB alignment method on the a-C:H thin film surface as working gas at 30W rf bias condition can be achieved.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 제6회 학술대회 논문집 일렉트렛트 및 응용기술연구회
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• pp.23-26
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• 2004

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of a Carbon Nitride (NDLC) thin film. NDLC thin film exhibits high electrical resistivity and thermal conductivity that are similar to the properties shown by diamond-like carbon (DLC) thin films. The diamond-like properties and nondiamond-like bonding make NDLC an attractive candidate for applications. A high pretilt angle of about $9.9^{\circ}$ by ion beam (IB) exposure on the NDLC thin film surface was measured. A good LC alignment is achieved by the IB alignment method on the NDLC thin film surface at annealing temperature of $200^{\circ}C$. The alignment defect of the NLC was observed above annealing temperature of $250^{\circ}C$. Consequently, the high pretilt angle and the good LC alignment by the IB alignment method on the NDLC thin film surface can be achieved.

• International Journal of Aeronautical and Space Sciences
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• 제14권1호
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• pp.19-29
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• 2013

This paper deals with the study of buckling, vibration, and parametric instability characteristics in a damaged cross-ply and angle-ply laminated plate like beam under in-plane harmonic loading, using the finite element approach. Damage is modelled using an anisotropic damage formulation, based on the concept of reduction in stiffness. The effect of damage on free vibration and buckling characteristics of a thin plate like beam has been studied. It has been observed that damage shows a strong orthogonality and in general deteriorates the static and dynamic characteristics. For the harmonic type of loading, analysis was carried out on a thin plate like beam by solving the governing differential equation which is of Mathieu-Hill type, using the method of multiple scales (MMS). The effects of damage and its location on dynamic stability characteristics have been presented. The results indicate that, compared to the undamaged plate like beam, heavily damaged beams show steeper deviations in simple and combination resonance characteristics.

• KCI Concrete Journal
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• 제14권3호
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• pp.111-120
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• 2002

This study proposes a joint model consisting of different types of members as a new structural system, and then investigates the resulting structural behavior. The joint model consists of a concrete-filled steel tube column (CFT) together with a steel reinforced concrete at the end plus reinforced concrete beam at the center. For comparison, two other joint models were designed, that are, a CPT with a reinforced concrete beam, and a CFT with a steel reinforced concrete at the end plus steel concrete beam at the center, then their joint capacity and rigidity, energy absorption capacity, etc., were all investigated. From the results, the CFT column with a steel reinforced concrete at the end plus steel concrete beam at the center was outstanding in terms of its capacity and rigidity. The results of this analysis demonstrate that an adequate connection type and reinforcement method with different materials of increasing the rigidity, thereby producing a capacity improvement along with protection from pre-fractures.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.839-844
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• 2002

This letter focuses on the liquid crystal alignment characteristics according to the properties of hydrogenated amorphous carbon(a-C:H) thin film deposited by RPECVD(Remote Plasma Enhanced Chemical Vapor Deposition) method using $C_2H_2$ and He gases. The properties of the deposited thin films were controlled by the ion beam irradiation time and ion beam energy. The results show that not ion beam energy but ion beam irradiation time plays an important role in the properties of a-G:H thin films. As the ion beam irradiation time increases, not only the sp2 concentration in a-G:H thin films but also liquid crystal pretilt angle was varied.