• Journal of the Optical Society of Korea
• /
• 제17권6호
• /
• pp.494-499
• /
• 2013

In this paper, we present an optical encryption and information authentication of 3D objects considering wireless channel characteristics. Using the optical encryption such as double random phase encryption (DRPE) and 3D integral imaging, a 3D scene with encryption can be transmitted. However, the wireless channel causes the noise and fading effects of the 3D transmitted encryption data. When the 3D encrypted data is transmitted via wireless channel, the information may be lost or distorted because there are a lot of factors such as channel noise, propagation fading, and so on. Thus, using digital modulation and maximum likelihood (ML) detection, the noise and fading effects are mitigated, and the encrypted data is estimated well at the receiver. In addition, using computational volumetric reconstruction of integral imaging and advanced correlation filters, the noise effects may be remedied and 3D information may be authenticated. To prove our method, we carry out an optical experiment for sensing 3D information and simulation for optical encryption with DRPE and authentication with a nonlinear correlation filter. To the best of our knowledge, this is the first report on optical encryption and information authentication of 3D objects considering the wireless channel characteristics.

• 한국광학회지
• /
• 제20권2호
• /
• pp.128-133
• /
• 2009

본 연구에서는 광원을 내장하고 있는 포인팅 펜(pointing pen)의 출력광과 광 도파로 배열 사이의 광 결합을 이용하여 펜의 접촉여부와 접촉 위치를 검출하는 광학식 터치 패널 장치를 제안한다. 펜의 출력광과 광 도파로 배열 간의 광 결합을 최대화하고, 동시에 특정 광 도파로로 결합된 광속이 적은 손실로 전파할 수 있도록 하기 위해 광 도파로의 교차점 마다 부가적인 피라미드 구조를 삽입하였다. 광 도파로 단면의 크기가 $50{\times}50{\mu}m^2$인 경우 광선 추적법을 통해 결정된 피라미드의 최적 구조는 밑변의 폭, 높이, 경사각이 각각 $50{\mu}m$, $22.5{\mu}m$, $42^{\circ}$이었다. 이때 광 결합 효율은 97.8%이었으며, 전파손실은 평균적으로 0.3 dB/mm이었다. 그리고 펜의 기울어짐에 대한 허용 각도는 ${\pm}12^{\circ}$임을 확인하였다.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 1997년도 제15회 KOSCO SYMPOSIUM 논문집
• /
• pp.153-162
• /
• 1997

The effects of tumble and swirl flows on the flame propagation were investigated experimentally in a 4-valve optical gasoline engine. The tumble flow patterns, generated by various intake ports of different entry angle; $25^{\circ}$ , $20^{\circ}$ and $15^{\circ}$ , were characterized under motored conditions with laser Doppler velocirnetry. Inclined tumble(swirl) flows were induced by three different swirl control valves. The initial flame propagation was visualized by an ICCD camera and its image were analyzed to compare the enflamed area and displacement of initial flames. It was found that there is a correlation between the stronger tumble during induction and turbulence levels at the time of ignition resulting in faster flame development. Inclined tumble was proved to be more beneficial than the pure tumble for faster and stable combustion under lean mixture conditions, which was confirmed by faster propagating flame images.

• 한국전산유체공학회지
• /
• 제15권2호
• /
• pp.14-20
• /
• 2010

Shock-focusing concave reflectors can have parabolic, circular or elliptic cross-sections. They produce effectively a very high pressure at the focusing point. In the past, many optical images have been obtained on shock focusing via experiments. Measurement of field variables is, however, difficult in the experiment. Using the wave propagation algorithm and the Cartesian embedded boundary method, we have successfully obtained numerical Schlieren images that appear very much like the experimental results. In addition, we obtained the detailed field variables such as pressure, velocity, density and vorticity in the unsteady domain. The present numerical results have made it possible to understand the shock focusing phenomenon in more detail than before.

• 한국자동차공학회논문집
• /
• 제7권6호
• /
• pp.57-64
• /
• 1999

Initial flame development and propagation were visualized under the new ignition system developed to estimate the effects of ignition characteristics on the engine performance in a port injection SI engine. Effects of intake air flow characteristics were also investigated by three different kinds of the swirl control valve. Experiments were performed in an optical single cylinder engine modified form a commercial engine. Flame images were captured through the quartz window mounted in the piston by the high speed video camera and analyzed to compare initial flame development. Results show that IMEP tends to rise slightly as the ignition duration gets longer. The direction of flame propagation is decisively governed by the in-cylinder flow motion. Every flame grows toward the exhaust valve forming a kind of turbulent flame. Initial flame propaagation characteristics are very similar to ones analyzed form pressure data.

• Journal of Astronomy and Space Sciences
• /
• 제32권2호
• /
• pp.151-159
• /
• 2015

The fundamental conception in physics of the propagation of the electromagnetic wave polarization in matter is newly understood as the cardinal keyword in free-space quantum communication technology and cosmology in astrophysics. Interactive visualization of the propagation mechanism of polarized electromagnetism in a medium with its helicity has accordingly received attention from scientists exploiting the protocol of quantum key distribution (QKD) to guarantee unconditional security in cryptography communication. We have provided a dynamic polarization platform for presenting the polarization modes of a transverse electromagnetic wave, converting the state of polarization through the arrangement of optical elements, using Jones vectors calculations in Methematica. The platform graphically simulates the mechanism of production and propagation of the polarized waves in a medium while satisfying Maxwell's equations.

• 대한기계학회논문집
• /
• 제19권8호
• /
• pp.2030-2038
• /
• 1995

In this study, three turbulent flame propagation models are compared using experimentally measured data of a 4 valves/cylinder spark-ignition engine. First two conventional models are B.K model and GESIM combustion model. The burning rates calculated from the two models are compared with the burning rates calculated from measured pressure data using the one-zone heat release analysis. GESIM combustion model predicts burning rates closer to the data acquired from the experiment in wide operating ranges than B-K model does. The third model is refined based on GESIM combustion model by including the effect of flame stretch, turbulent length scale band pass filter and a variable that considers flame size and the area of flame contacting the cylinder wall surface. The refined combustion model predicts burning rates closer to experimental results than GESIM combustion model does. Also, the refined combustion model predicts flame radius close to the experimental result measured by using optical fiber technique.

• 한국광학회지
• /
• 제10권2호
• /
• pp.174-177
• /
• 1999

FHD (Falme Hydrolysis Deposition) 공정으로 실리카 슬렙도파로를 제작하고 전송손실을 측정하였다. 전송손실 측정에는 프리즘커플링으로 빛을 입사시키고 굴절률 정합액으로 출사시키는 장치를 제작 사용하였다. 측정된 전송손실은 1300 nm 및 633 nm에서 각각 0.04 dB/cm 및 0.09 dB/cm의 값을 보였다.

• Macromolecular Research
• /
• 제12권5호
• /
• pp.437-442
• /
• 2004

We have fabricated a polymeric waveguide by using a hot embossing technique and have investigated its propagation loss. The replication of waveguide channels through the use of a hot embossing technique is of interest as a single-step process that could deliver surface roughnesses far smaller than the wavelength. We have evaluated experimentally that the sidewall roughness has a dominant effect on insertion losses of the multimode polymeric waveguide. The propagation loss of the waveguide decreased dramatically upon decreasing the sidewall roughness of the channel. We have confirmed that the preparation of waveguides having nanometer-scale sidewall roughness and 0.1 dB/cm propagation loss is possible when using the hot embossing technique.

• 한국광학회지
• /
• 제18권3호
• /
• pp.226-231
• /
• 2007

본 논문에서는 이중 금속선으로 이루어진 다양한 곡선형 도파로를 고려하고 이 구조들에서 전파하는 모드의 특성을 수치해석적으로 분석하였다. 이중 금속선들 간의 간격과 내부 유전체의 굴절률 변화에 따라 곡선형 도파로의 최적 반경과 최소손실의 경향을 조사하였으며, 그 결과 이중 금속선 구조가 단일 금속선 구조보다 전파특성이 좋은 최적 구조가 존재함을 확인하였다.