• Journal of Sensor Science and Technology
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• v.18 no.2
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• pp.173-178
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• 2009

In this study, we have fabricated a fiber-optic dosimeter using an organic scintillator and a plastic optical fiber for measuring percentage depth dose with high energy X-ray beam. The scintillating light generated in organic sensor probe embedded in a solid water are guided by 20 m plastic optical fiber to the light-measuring device such as a photodiode- amplifier system. Using a fiber-optic dosimeter and an ion chamber, percentage depth dose curves are measured with 6 and 15 MV energies of X-ray beam whose field sizes are $2\;cm\;{\times}\;2\;cm$ and $10\;cm\;{\times}\;10\;cm$.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.4
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• pp.867-871
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• 2012

In this paper, we proposed and demonstrated a low loss $1{\times}4$ type plastic optical fiber(POF) coupler incorporating a polymer tapering waveguide region. To avoid leakage loss at the interfaces between the POF and the polymer waveguide, we employed two POF transition regions, in which the cross section of the POF is adiabatically converted from a circular to a rectangular shape without change of its cross-section area. The device was fabricated based on a injection mold made of a silicon rubber. The fabricated POF coupler showed 1.33 dB of excess loss and 2.2 dB of flatness.

• Journal of the Korean Solar Energy Society
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• v.31 no.1
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• pp.31-36
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• 2011

CF(Circular Fresnel) POF(Plastic Optical Fiber) daylighting system is a beam daylighting system utilizing solar direct beam radiation. In this study, a CF POF daylighting system has been introduced, developed and applied to KIER test buildings. The CF POF daylighting system consists of three parts: light collector, light transmitter and light diffuser. The light collector includes a Circular Fresnel lens focusing solar direct illuminance by sun tracking. The light transmitter contains the POF cable which has light transmission loss of 4.5% per meter. The light diffuser has about 80% diffuser efficiency. This study aims to evaluate of POF daylighting system performance. At the results of a CFPOF system performance evaluation, the theoretical CFPOF system efficiency was 41.9% and the actual CFPOF system efficiency at the KIER test building was 37.5%. The difference was due partly to the connecting efficiency.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3398-3402
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• 2022

We fabricated a 15 m long position-sensitive plastic scintillation optical fiber (PSOF) detector consisting of a PSOF, two photomultiplier tubes, four fast amplifiers, and a digitizer. A single PSOF was used as a sensing part to estimate the gamma-ray source position, and ¹³⁷Cs, an uncollimated solid-disk-type radioactive isotope, was used as a gamma-ray emitter. To improve the sensitivity, accuracy, and measurement time of a PSOF detector compared to those of previous studies, the performance of the amplifier was optimized, and the digital signal processing (DSP) was newly designed in this study. Moreover, we could measure very low dose rates of gamma-rays with high sensitivity and accuracy in a very short time using our proposed PSOF detector. The results of this study indicate that it is possible to accurately and quickly locate the position of a very low dose rate gamma-ray source in a wide range of contaminated areas using the proposed position-sensitive PSOF detector.

• Journal of the Optical Society of Korea
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• v.16 no.3
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• pp.247-255
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• 2012

Daylighting has a very effective role in reducing power consumption and improving indoor environments in office buildings. Previously, it was not under consideration as a major source of renewable energy due to poor reliability in the design. Optical fiber as a transmission medium in the daylighting system demands uniform distribution of light to solve cost, heat, and efficiency issues. Therefore, this study focuses on the uniform distribution of sunlight through the fiber bundle and to the interior of the building. To this end, two efficient approaches for the fiber-based daylighting system are presented. The first approach consists of a parabolic mirror, and the second approach contains a Fresnel lens. Sunlight is captured, guided, and distributed through the concentrator, optical fibers, and lenses, respectively. At the capturing stage, uniform illumination solves the heat problem, which has critical importance in making the system cost-effective by introducing plastic optical fibers. The efficiency of the system is increased by collimated light, which helps to insert maximum light into the optical fibers. Furthermore, we find that the hybrid system of combining sunlight and light emitting diode light gives better illumination levels than that of traditional lighting systems. Simulation and experimental results have shown that the efficiency of the system is better than previous fiber-based daylighting systems.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.84-85
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• 2000

현재 세계의 통신업계들은 인터넷, 멀티미디어 서비스 등의 발전에 따라 폭발적인 전송 속도의 증가를 예측하고 있다. 대용량의 정보를 초고속으로 전달하기 위한 방법으로 각광 받고 있는 광통신은 사무실의 네트웍, 가정의 전자용품, 항공기내 정보시스템 구축, 인터넷 화상 통신등에 이용되고 있다. 최근에는 플라스틱 광섬유(POF; plastic optical fiber)에 관한 연구가 활발히 이루어지고 있다. 기존의 구리 전선이 가지는 단점인 전자기적 간섭과 무거운 중량을 극복한 것이 유리 광섬유이다. 그러나, 이 유리 광섬유는 제작비용이 비싸고 다루기 힘들다는 단점이있다. 이러한 요구속에 개발된 것이 플라스틱 광섬유이다. 플라스틱 광섬유는 다루기 쉬울 뿐아니라 가벼운 장점이있다. (중략)

• Journal of Sensor Science and Technology
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• v.15 no.4
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• pp.297-301
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• 2006

We have fabricated a multi-mode nonlinear plastic optical fiber (POF) using organic nonlinear optical materials and demonstrated the propagation of light. The refractive indices of core and cladding are 1.5240 and 1.5172. We made a POF preform by rod-in tube method. The core diameter of the fabricated POF is about $30{\mu}m$. We evaluated the temperature characteristics of POF. The sensitivity is $0.345{\;}mW/^{\circ}C$ and the linearity of sensor was good.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.245-245
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• 2007

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.241-244
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• 2012

In this paper, three types of optical receivers are designed using a $0.35-{\mu}m$ standard CMOS technology for plastic optical fiber (POF) applications. Basic common-source transimpedance amplifier (CS-TIA), common-gate TIA (CG-TIA), and regulated-cascode TIA (RGC-TIA) are optimally designed, and their transimpedance gain (TZ gain), 3-dB bandwidth, and noise characteristics are compared and analyzed. As a result of simulations, the RGC-TIA indicates better TZ gain and 3-dB bandwidth than other topologies, and CS-TIA has the best noise performance. Each optical receiver occupies area of $0.35mm^2$.

• Korean Journal of Optics and Photonics
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• v.12 no.2
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• pp.135-142
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• 2001

Recently, plastic optical fiber draws a lot of attention as a new transmission medium for local area network (LAN) and home network applications. As PMMA based GI-POF (Graded Index Plastic Optical Fiber) has very low loss at about 500 nm and 650 nm wavelengths, it is very important to have a compact ultra short optical pulse source at these wavelength windows. In this paper, we have investigated detailed characteristics of gain switched laser system by using a commercially available low cost RF devices and an InGaAlP Fabry Perot semiconductor laser operating at 650 nm wavelength. The shortest optical 'pulse obtained was 33 psec with 1 GHz repetition rate. Depending on the DC bias current and the modulation frequency, the FWHM and the pulse energy of the gain switched pulses show 33.3-82.8 psec and 0.97-9.69 pI respectively. Also, the spectral bandwidths for CW and gain switched operations are 0.44 nm and 1.50 nm. We believe that these results are quite useful for high bit rate optical transmission applications with PMMA based plastic optical fibers in addition to estimate properties of ultra fast optical components and electro-optic devices. vices.