• 한국광학회지
• /
• 제17권2호
• /
• pp.159-164
• /
• 2006

원통형의 압접소자를 이용한 광지연선을 사용하여 광 간섭형 단층촬영 시스템을 제작하였다. 광지연선은 18 m 길이의 단일 모드 광섬유를 압전소자의 둘레에 134회 감아 구성하였으며 0.78 mm의 광경로 길이변화를 얻었다. 제작한 광 간섭형 단층촬영 시스템은 신호 대 잡음비 96.9 dB, 종방향 분해능 $18.6{\pm}0.5\;{\mu}m$, 횡방향 분해능 $5\;{\mu}m$의 특성을 보였다.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2009년도 동계학술발표회 논문집
• /
• pp.507-508
• /
• 2009

We have proposed and demonstrated noncontact refractometer incorporating a fiber bundle. The fiber bundle is composed of a TEC(thermally expended core) fiber and hundreds multimode fibers. The fiber is designed in such a way that the detected reflected optical power from a liquid is constant against the distance between fiber bundle and liquid surface. Low differactive characteristic of TEC fiber make it possible to increase the available distance between the fiber bundle and liquid surface, The obtained sensitivity, optical intensity variation by change of refractive index of liquid is 0.4.

• 한국고분자학회:학술대회논문집
• /
• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
• /
• pp.23-24
• /
• 2006

Magnetic and magneto-optical properties of regioregular (>99%) poly(3-dodecylthiopenes are investigated. Faraday rotation of spin-coated films show extremely large Verdet constants, falling strongly with decreasing regioregularity. EPR spectroscopy at room temperature shows the presence of about 1 spin/190 monomers, indicative of delocalisation beyond a single polymer chain. SQUID measurements on the polymer give an effective magnetic moment of about 48900 mB, corrsponding to a S-value of 25.000. The Weiss-constant is 1.33 K indicating ferromagnetic coupling. Our experimental results show that organic polymer magnets can be prepared. Large MO effects allow the use of these materials in all-organic MO-sensors and devices.

• 대한전자공학회논문지
• /
• 제25권4호
• /
• pp.402-406
• /
• 1988

The MgGa2Se4 single crystal for study of optical properties is for the first time grown by Bridgmna method. The crystal structure of grown MgGa2Se4 single crystal has the Rhomobohedral structure (R3m) and its lattice constant are a=3.950\ulcorner c=38.893\ulcornerin Hexagonal structure. The energy band structure of grown MgGa2Se4 single crystal structure has direct band gap and the optical energy gap measured from optical absorption in this crystal is 2.20eV at 290K. The temperature dependence of energy gap was given Eg(T)=Eg(O)-aT\ulcorner)B+T), from varshni equation, where Eg(O)=2.34eV, a=8.79x10**-4eV/and b=250K.

• 한국전기전자재료학회논문지
• /
• 제11권3호
• /
• pp.237-241
• /
• 1998

In this study, PLZT stock solutions around x/65/35 (x=6~11) ferroelectric region were prepared by Sol-Gel method and deposited on ITO-glass by spin-coating method. The thin films were annealed by RTA(rapid thermal annealing). The variations of crystallographic structure of the thin films were observed using XRD and hysteresis curves, dielectric characteristics, and optical transmittances were measured in order to investigate the characteristics of the thin films. The thin films were crystallized at $750^{\circ}C$ for 5 min by RTA. Relative dielectric constant and optical transmittance increased with increasing La content, Ec and Pr were higher for thin films than for bulk materials.

• Journal of the Optical Society of Korea
• /
• 제13권3호
• /
• pp.373-378
• /
• 2009

An Ethernet passive optical network (EPON) is a low-cost, high-speed solution to the bottleneck problem of a broadband access network. This paper analyzes the delay and the jitter performance of dynamic bandwidth allocation (DBA) schemes for differentiated services in EPONs. Especially, the average packet delay and the delay jitter of the expedited forwarding (EF) traffic class are compared, with consideration as to whether a cyclic or an interleaved polling scheme is superior. This performance evaluation reveals that the cyclic polling based DBA scheme provides constant and predictable average packet delay and improved jitter performance for the EF traffic class without the influence of load variations.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 추계학술대회 논문집 광주전남지부
• /
• pp.114-118
• /
• 2006

We investigated the transient electroluminescence (EL) and modulation characteristics of red organic light-emitting diodes (OLEDs), which consist with 4-(dicyanomethylene)-2-i -propyl-6-(1,1,7,7-tetramethyljulolidyl-9-cnyl)-4H-pyran (DCJTI) and rubrene doped into tris(8-hydroxyquinoline)aluminum ($Alq_3$). The transient EL waveforms showed two components, the overshooting peak and constant component, indicating that the excess amount of accumulated charges simultaneously recombine at the onset moment. This overshooting effect reduced the rise time of transient EL and enhanced the optical output of OLEDs when the pulse voltage applied to the device. We demonstrated that the red OLEDs could be use for the high-speed switching application by driving at more than 100 MHz and transmitting the video signals utilized as the electro-optical conversion device

• 센서학회지
• /
• 제30권4호
• /
• pp.196-203
• /
• 2021

In this study, an optical identification system was developed, wherein visible light is used to transmit the interrogating signal, and infrared is used to send the response signal. In the reader, visible light from a light emitting diode (LED) array was modulated via modified pulse width modulation for flicker-free illumination and dimming control. Moreover, the duty factor of the dimming control time was employed to control the illumination from the LED. In the transponder, the spike signal in the output of the high-pass filter was utilized to recover the interrogating signal while preventing interference from the 120-Hz noise from adjacent lighting lamps. The illumination was controlled in 26-86% range of the constant wave LED illumination by changing the duty factor from 20% to 90%. This configuration is advantageous for the construction of optical identification systems for automatic security check and car fare calculation at toll gates or parking facilities.

• Current Optics and Photonics
• /
• 제5권1호
• /
• pp.16-22
• /
• 2021

We present the Shannon entropy as an indicator of the spatial resolutions of the morphologies of the resonance mode patterns in an optical resonator. We obtain each optimized number of mesh points, one of minimum size and the other of maximum one. The optimized mesh-point number of minimum size is determined by the identifiable quantum number through a chi-squared test, whereas the saturation of the difference between Shannon entropies corresponds to the other mesh-point number of maximum size. We also show that the optimized minimum mesh-point increases as the (real) wave number increases and approximates the proportionality constant between them.

• 한국광학회지
• /
• 제10권1호
• /
• pp.21-26
• /
• 1999

광학적 입자열 측정법을 사용하여 공칭크기가 1, 2, 3, 5, 그리고 10$\mu$m인 플로스티렌 표준구의 평균지름을 측정하고 불확도를 분석하였다. 광학적 입자열 측정법이란, 슬라이드 글라스 위에 표준입자를 6각형 구조로 배열시킨 후, 입자열의 길이를 측정하고 이를 입자의 개수로 나누어 평균지름을 구하는 평균지름을 구하는 방법을 말하는데, 본 연구에서는 CCD 카메라와 화상처리를 도입함으로써 기존의 목측에 의한 측정방법보다 정확하고 편리하게 측정할 수 있도록 하였다. 입자열의 현미경 상을 CCD카메아로 얻은 후 소프트웨어 필터를 적용시켜 입자열의 길이를 화면의 픽셀단위로 측정하였으며, 이를 실제 길이로 환산하기 위해, 스템이지 마이크로미터의 현미경 상에 역시 필터를 적용시켜 구한 길이환산계수응 곱하였다. 이 길이를 입자열을 이루는 입자의 개수로 나누고, 공기층에 의한 입자의 찌그러짐 효과를 보정한 결과, 각 입자의 평균지름은 제조 회사의 인증값과 0.7% 이내로 일치하였며, 측정불확도는 1.5% 이내로 얻어졌다.