광원을 내장한 펜의 출력광과 광 도파로의 광 결합을 이용하는 터치 패널 장치의 내부 광 결합 구조 설계

박대서,김대종,오범환,박세근,이일항,이승걸,Park, Dae-Seo,Kim, Dae-Jong,O, Beom-Hoan,Park, Se-Geun,Lee, El-Hang,Lee, Seung-Gol 한국광학회 2009 한국광학회지 Vol.20 No.2

In this paper, an optical touch panel device is newly proposed, with operating principle based on the optical coupling between a pointing pen having a built-in light source and perpendicularly crossed optical waveguide arrays. In order to enable an external light to couple into a waveguide core, the auxiliary pyramidal structures are introduced into all intersecting points located periodically along optical waveguides. The shape is optimized for minimizing the unwanted propagation loss due to the same structure by a ray tracing method. For the optical waveguide with the size of $50{\times}50{\mu}m^2$, the bottom width, height, and slope angle of the optimized pyramidal structure are $50{\mu}m$, $22.5{\mu}m$, and $42^{\circ}$, respectively. The optical coupling efficiency of about 97.8% and the average propagation loss of 0.3 dB/mm were achieved for the optimized touch panel. Finally, it is found from the tolerance analysis that tilting of the pen up to ${\pm}12^{\circ}$ can be allowed.

연속굴절률분포 렌즈 제작을 위한 봉 - 형 라디칼 중합방법

정상돈(Sang Don Jung),이일항(El Hang Lee),이정익(Jeong Ik Lee),심홍구(Hong Ku Shim) 한국화학공학회 1995 화학공학의이론과응용 Vol.1 No.2

광선추적법 기반의 적분구 분석 시뮬레이터에서 OpenMP 지시어를 이용한 속도 향상 및 몬테카를로 방법의 무작위성 보장

김승용,김대찬,오범환,박세근,이일항,이승걸,Kim, Seung-Yong,Kim, Dae-Chan,O, Beom-Hoan,Park, Se-Geun,Lee, El-Hang,Lee, Seung-Gol 한국광학회 2011 한국광학회지 Vol.22 No.2

In order to improve the calculation speed of an integrating-sphere simulator based on a ray-tracing method, parallel processing with OpenMP directive was implemented into the simulator and the randomness of Monte Carlo method was guaranteed by utilizing a parallel random number generator. It was confirmed that simulation results obtained with more than $10^7$ rays showed good agreement with theoretical results within the error range of 0.5%, and that the calculation speed improved as the number of threads increased. Finally, the spatial response distribution functions of a real integrating sphere were simulated and compared with previous results.

가간섭 영역 외의 배경 잡음성 간섭무늬 신호 필터링을 통한 백색광 주사간섭계의 성능 향상

임해동,이민우,이승걸,박세근,이일항,오범환,Yim, Hae-Dong,Lee, Min-Woo,Lee, Seung-Gol,Park, Se-Geun,Lee, El-Hang,O, Beom-Hoan 한국광학회 2009 한국광학회지 Vol.20 No.5

In order to enhance the background noise filtering performance of the white light interferometry(WLI), we demonstrate the noise filtering performance of preprocessing of the measured fringe signals. The WLI was realized through a mirau interferometer which was equipped with a green LED. When measuring large-height and rough surface objects, the illumination optics are considered the numerical aperture(NA) and the depth of focus(DOF). In this case, the limited NA of the illumination optics has a considerable impact on the interference fringe. Therefore, we propose a preprocessing method that uses the intensity difference between the measured intensity and the moving average intensity. The performance is demonstrated by measuring an array of metal solder balls fabricated on printed circuit board(PCB). The proposed method reduces the noise pixels by 15 percent.

높이영상에 산포되어 있는 점 노이즈 처리를 통한 백색광 간섭계의 영상 복원력 향상

임해동,이민우,이승걸,박세근,이일항,오범환,Yim, Hae-Dong,Lee, Min-Woo,Lee, Seung-Gol,Park, Se-Geun,Lee, El-Hang,O, Beom-Hoan 한국광학회 2010 한국광학회지 Vol.21 No.1

In this paper, in order to enhance the image reconstruction performance of white light scanning interferometry(WLI), we demonstrate the scattered point noise filtering performance of post-processing methods. Median filtering is similar to using an averaging filter. Because the median value is less sensitive than the mean to extreme values, the median filter can remove the scattered point noise from a height-map without significantly reducing the sharpness of the image. In several specific cases, however, the median filter can't remove the scattered point noise. Therefore, we propose a comparative mean filter that uses order-statistic filtering and the mean of the neighborhood pixels. The performance is demonstrated by measuring an array of metal solder balls fabricated on PCB. The proposed method reduced the noise pixels by 4.4 percent.

유한 반경의 시준 광속을 이용한 투명 매질의 두께와 굴절률의 동시 측정

박대서,오범환,박세근,이일항,이승걸,Park, Dae-Seo,O, Beom-Hoan,Park, Se-Geun,Lee, El-Hang,Lee, Seung-Gol 한국광학회 2009 한국광학회지 Vol.20 No.1

본 연구에서는 저간섭성 반사계(Optical low-coherence reflectometry)를 이용하여 한 번의 측정으로 투명 시료의 두께와 굴절률을 동시에 측정하는 기술을 제안하였다. 제안된 방법은 유한 반경을 가진 시준된 광속을 시료의 경계 영역으로 입사시키는 것으로써, 시료가 있는 부분과 없는 부분으로부터 반사된 광속에 의한 간섭 무늬들을 한 번에 획득할 수 있다. 한번의 측정을 통해 얻어진 두 종류 간섭 무늬들의 상대적인 위치 차이를 이용하여 시료의 두께와 굴절률을 동시에 결정할 수 있었다. 굴절률의 정밀도는 이송장치의 위치 정밀도가 향상되고, 시료의 두께가 두꺼워 질수록 개선될 수 있으며, 본 실험에서는 약 $10^{-3}$의 정밀도로 굴절률을 결정할 수 있었다.

방향성 결합기 소멸비 특성의 일반화 경향과 파장분리기의 소형화 설계

최철현,오범환,이승걸,박세근,이일항,Choi, Chul-Hyun,O, Beom-Hoan,Lee, Seung-Gol,Park, Se-Geun,Lee, El-Hang 한국광학회 2005 한국광학회지 Vol.16 No.5

In a directional coupler, the design process requires repeated calculation of the characteristics of every changed structure, because it is generally difficult to expect the extinction ratio to be optimized over the entire variation of design parameters. In this paper, we systematically simulated the extinction ratio as a function of the design parameters, and analyzed the general tendency of that characteristic. In other words, we could find the generalized extinction ratio curve if the separation distance is normalized by the waveguide width. Here, the extinction ratio is shown to be increased as the normalized frequency (v) and the ratio (d) of the separation distance over the waveguide width were increased. For various structures with same ratio d, all corresponding extinction ratio curves as a function of v coincide with each other. We showed the usefulness of the generalized extinction ratio curve by applying it to the design and the fabrication of 1310/l550 nm demultiplexer, as it was convenient to design a shorter directional coupler with targeted extinction ratio from this curve.

Transient Behaviour of Photorefractive Bi₁₂SiO20 Crystal : Two Wave Mixing with an External A.C. Field

곽종훈(Chong Hoon Kwak),이일항(El-Hang Lee),Jeno Takacs,Laszlo Solymar 한국광학회 1993 한국광학회지 Vol.4 No.1

광굴절결정에 구형파 및 정현파형의 외부 전장을 인가할 때 유기되는 공간 전하장의 시간 종속 해를 해석적으로 유도하였다. Bi₁₂SiO_(20) 결정에 최대 7 KV/㎝ (주파수<1 KHz)의 전장을 가하면서 시간 종속적인 2광파 혼합의 이득 변화를 측정하고 이론치와 정량적으로 비교 분석하였다. The temporal differential equation describing the build-up of the space-charge field in the presence of square and sinusoidal alternating field in photorefractive materials is solved analytically. We also measured the average two-wave mixing gain and the full temopral gain variations in a Bi₁₂SiO_(20) crystal with applied fields of up to 7 KV/㎝ amplitude and 1 KHz repetition rate. It has been found that the experimental measurements agree well with the theoretical results.

적응형 보쉬공정(Adaptive Bosch Process)을 이용한 식각된 바닥면 연구

이승용(Seung-Yong Lee),양승국(Seung-Kook Yang),김한형(Han-Hyoung Kim),유한석(Han-Suk Yoo),신상현(Sang-Hyun Sin),장동훈(Dong-Hoon Chang),이일항(El-Hang Lee),오범환(Beam-Hoan O),이승걸(Seung-Gol Lee),박세근(Se-Geun Park) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.7

We do not use dedicated Bosch process equipment of high cost, it is uses Bosch process that fit existent ICP(Inductively Coupled Plasma) equipment. Bosch process which is method of deep silicon etching is connected repeatedly in using SF? Plasma for etching process and using C₄F? Plasma the deposition process. However, between etching bottom layer and side wall not verticality and curved layer is formed. It is used about this curved layer phenomenon. because of considering gas fraction, temperature, substrate voltage, process time etc. It is used about this curved layer phenomenon and suggested optimum process condition. Standard process for study of process gas used SF? and Ar, and source power 600W, substrate voltage used -200V. Deposition process used C₄F? gas, and source power 600W, substrate voltage did not used. Process substrate temperature makes via 0℃ and progressed study. Through these processing condition, we manufactured mold for NIL(Nano Imprint Lithography) process.

Implicit와 explicit 방법의 결합에 의한 3차원 유한차분 빔전파 방법의 개선

김현준,오범환,박세근,이일항,이승걸,Kim, Hyun-Jun,O, Beom-Hoan,Park, Se-Geun,Lee, El-Hang,Lee, Seung-Gol 한국광학회 2004 한국광학회지 Vol.15 No.6

We propose a hybrid method combining the implicit with the explicit methods in order to reduce the calculation time and improve the convergence problem of the 3-dimensional finite-difference beam propagation method. The numerical simulation of a directional coupler is carried out by the proposed method. It is found from the simulation results that the calculation speed of our method is 10 times faster than that of direct solving techniques.