• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.976-979
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• 2002

A focusing grating coupler (FGC) was not fabricated by the 'Continuous Path Control' writing strategy but by an electron-beam lithography system of more general exposure mode, which matches not only the address grid with the grating period but also an integer multiple of the address grid resolution (5 nm), To more simplify the fabrication, we are able to reduce a process step without large decrease of pattern quality by excluding a conducting material or layer such as metal (Al, Cr, Au), which are deposited on top or bottom of an e-beam resist to prevent charge build-up during e-beam exposure. A grating pitch period and an aperture feature size of the FGC designed and fabricated by e-beam lithography and reactive ion etching were ranged over 384.3 nm to 448.2 nm, and $0.5{\times}0.5mm^2$ area, respectively, This fabrication method presented will reduce processing time and improve the grating quality by means of a consideration of the address grid resolpution, grating direction, pitch size and shapes when exposing. Here our investigations concentrate on the design and efficient fabrication results of the FGC for coupling from slab waveguide to a spot in free space.

• Transactions on Electrical and Electronic Materials
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• 제3권1호
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• pp.30-37
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• 2002

A focusing grating coupler (FGC) was not fabricated by the 'Continuous Path Control'writing strategy but by an electron-beam lithography system of more general exposure mode, which matches not only the address grid with the grating period but also an integer multiple of the address grid resolution (5 nm). To more simplify the fabrication, we are able to reduce a process step without large decrease of pattern quality by excluding a conducting material or layer such as metal (Al, Cr, Au), which are deposited on top or bottom of an e-beam resist to prevent charge build-up during e-beam exposure. A grating pitch period and an aperture feature size of the FGC designed and fabricated by e-beam lithography and reactive ion etching were ranged over 384.3 nm to 448.2 nm, and 0.5 $\times$ 0.5 mm$^2$area, respectively. This fabrication method presented will reduce processing time and improve the grating quality by means of a consideration of the address grid resolution, grating direction, pitch size and shapes when exposing. Here our investigations concentrate on the design and efficient fabrication results of the FGC for coupling from slab waveguide to a spot in free space.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.1043-1046
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• 2003

We investigated the EO performances of the UV aligned twisted nematic liquid crystal display (TN-LCD) with the UV exposure on a-C:H thin film surface. LC alignment using UV exposure on the a-C:H thin film surface was achieved. Monodomain alignment of the UV aligned TN-LCD can be observed. An good EO characteristics of the UV aligned TN-LCD was observed with oblique ion beam exposure on the a-C:H thin film surface. Therefore, the EO property of the UV-aligned TN-LCD with UV exposure on the a-C:H thin film surface is almost the same as that of the rubbing-aligned TN-LCD on a polyimide (PI) surface.

• 대한방사선기술학회지:방사선기술과학
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• 제23권2호
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• pp.27-32
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• 2000

It was produced radiation dosimeter used photo-diodes for which ionization by x-ray was applied and evaluated the value of utility in clinics as compared with ion-chamber. The result obtained were as follows : 1. Comparison of ion-chamber with photo-diode dosimeter's x-ray output by the change of x-ray tube voltage, and the ratio of ion-chamber to diode was $0.96{\sim}1.02$ which was not affected by x-ray beam quality. 2. The ratio of ion-chamber to diode was 0.96 by change of tube current and 0.97 by change of exposure time that is not affected by x-ray quantity. 3. The ratio of ion-chamber to diode was $0.97{\sim}1.04$ by thickness and $0.93{\sim}1.10$ by radiation field that is little affected by second ray quantity. 4. Reproducibility of photo-diode dosimeter was 0.011(CV) and it is a good result. 5. Photo-diode dosimeter was affected by the surface angle of detector over 30 degrees. Produced dosimeter was small, light, and meets good result compared with ionization chamber. It was expected come into wide use in clinic.

• 한국광학회지
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• 제15권4호
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• pp.309-312
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• 2004

레이저 홀로그래피 방법과 반응성 이온식각 방법(RIE: reactive ion etching)을 사용하여 2차원 광자결정을 제작하였다. 육변형(hexagonal) 및 사변형(square) 광자결정 격자는 첫 번째 레이저 노광 후 시편을 각각 60도 및 90도 회전하고 다시 두 번째 노광을 통하여 제작할 수 있었다. 또한 사변형 광자결정 격자의 나노컬럼(nanocolumn)의 크기와 주기는 레이저 입사각에 따라 각각 125∼145 nm, 220∼290 nm로 미세한 조정이 가능하였다. 마지막으로 CH$_4$/H$_2$ 가스를 이용한 반응성 이온식각 방법을 통하여 aspect ratio가 1.5 이상인 InP/InGaAsP nanocolumn을 제작 할 수 있었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.559-562
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• 2003

The effect of pretilt angle on viewing characteristics of an IPS cell is discussed. We calculated optical viewing angle in the IPS cell as function of pretilt angle from $0.5^{\circ}$ to $4^{\circ}$, so that we could confirm that low pretilt angle was profitable for wider viewing property. In order to verify the calculation, we made an IPS cell with very low pretilt angle by the alignment method using ion beam exposure. In the experiment, we confirmed that wider viewing characteristics can be achieved if lower pretilt angle was applied in IPS mode. And Ion beam alignment method was useful for low pretilt creation.

• 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.

• 한국전기전자재료학회논문지
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• 제17권7호
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• pp.760-763
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• 2004

We studied the nematic liquid crystaL(NLC) aligning capabilities using the new alignment material of a nitrogenated diamond-like carbon(NDLC) thin film. The 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 films 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.

• 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.

• Journal of Astronomy and Space Sciences
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• 제22권4호
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• pp.441-450
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• 2005

유기재료(organic material)는 위성이나 우주비행체의 열을 조절하고 우주환경에 직접 노출되는 것을 차단하기 위하여 가장 흔하게 사용되는 재료 중 하나이다. 본 논문에서는 지상설비를 이용하여 모사한 우주환경에서 유기재료의 물성변화를 관찰하였다. 대표적인 위성용 유기 열조절 재료 중 하나인 2mil ITO(Indium Tin Oxide) coated aluminized KAPTON을 실험 대상으로 선택하였다. 양성자에 의한 단일 우주환경효과를 실험하기 위하여, 한국 원자력의학원의 MC-50 싸이클로트론(cyclotron)을 이용하여 양성자를 조사(irradiation)하였으며, 조사조건은 지구궤도 주변 최고의 양성자 발생기록인 1972년 8월의 최고치 상황을 적용하였다. 조사에너지는 평균 관측에너지인 30MeV으로 고정하였으며, 등가 조사량은 우주노출 시간 1년, 3년, 5년 및 10년을 기준으로 설정하였다. 분석과정은 인장강도를 측정하여 정량적 물성저하를 확인하였고, 전계방출 전자주사현미경 등으로 결정성변화와 노출표면의 손상을 분석하였다.