• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.7 s.98
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• pp.746-752
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• 2005

In this paper, optical noise effect is reduced by using the loss characteristics of plastic fibers in an optical wireless system. The attenuation coefficient of a plastic fiber for the signal is different from that f3r the noise light, and the length difference between two fibers to the 2PD's behaves like a discriminative element. It is possible to eliminate the optical noise effect and detect only the signal without optical filters. The signal to noise ratio in a differential detector using fibers was 9.7 dB higher than in a single photodiode without optical fiber.

• Journal of Sensor Science and Technology
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• v.14 no.4
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• pp.244-249
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• 2005

In this study, radiation sensor tips are fabricated for remote sensing of X or gamma ray with inorganic scintillators and plastic optical fiber. The visible range of light from the inorganic scintillator that is generated by radiation source is guided by the plastic optical fiber and is measured by optical detector and power-meter. Two kinds of sensor tips are designed and fabricated such as film type and powder type. Many kinds of inorganic scintillators are used to fabricate both sensor tips, and the different wavelength of emitting lights from them are measured to determine the optimal inorganic scintillator which has maximum light output. As a radiation source X-ray generator and Ir-192 are selected to test a performance of sensor tip. It is expected that the fiber-optic radiation sensor is widely used in nuclear industry and medical applications due to its special characteristics such as good flexibility, easy in processing, long lengths and no interference to electro magnetic field.

• Korean Journal of Optics and Photonics
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• v.24 no.1
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• pp.17-22
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• 2013

High performance plastic optical fiber (POF) $N{\times}N$ star couplers are implemented based on fusing and combining technology. A set of cladding-removed POFs are fused into a solid body by heating and pressing them together to form the transition region between the input and output sides. The operation principle of the proposed star coupler is explained based on ray optics. To demonstrate the performance of the device, $2{\times}2$, $4{\times}4$ and $6{\times}6$ type POF couplers were fabricated and characterized. Performances of the POF star couplers were evaluated in terms of the flatness of the coupling ratios and excess losses.

• Journal of Sensor Science and Technology
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• v.21 no.2
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• pp.151-155
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• 2012

We have investigated a refractive index sensor based on a cladded plastic optical fiber taper. The optical transmission and sensing characteristics of the device were illuminated in terms of ray optics. The sensor devices showed that the optical transmittance strongly depends on the refractive index of the external medium surrounding the tapered region.

• Smart Structures and Systems
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• v.17 no.2
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• pp.297-311
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• 2016

Based on the distributed fiber optic sensing (DFOS) technique, plastic optical fibers (POFs) are attractive candidates to measure deformations of geotechnical structures because they can withstand large strains before rupture. Understanding the mechanical interaction between an embedded POF and the surrounding soil or rock is a necessary step towards establishing an effective POF-based sensing system for geotechnical monitoring. This paper describes a first attempt to evaluate the feasibility of POF-based soil deformation monitoring considering the POF-soil interfacial properties. A series of pullout tests were performed under various confining pressures (CPs) on a jacketed polymethyl methacrylate (PMMA) POF embedded in soil specimens. The test results were interpreted using a fiber-soil interaction model, and were compared with previous test data of silica optical fibers (SOFs). The results showed that the range of CP in this study did not induce plastic deformation of the POF; therefore, the POF-soil and the SOF-soil interfaces had similar behavior. CP was found to play an important role in controlling the fiber-soil interfacial bond and the fiber measurement range. Moreover, an expression was formulated to determine whether a POF would undergo plastic deformation when measuring soil deformation. The plasticity of POF may influence the reliability of measurements, especially for monitored geo-structures whose deformation would alternately increase and decrease. Taken together, these results indicate that in terms of the interfacial parameters studied here the POF is feasible for monitoring soil deformation as long as the plastic deformation issue is carefully addressed.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.48-49
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• 2002

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 통신 등에 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. (중략)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.468-472
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• 2005

This paper is to investigate the influence of the endface quality on the loss characteristics of a plastic optical fiber connector for in-car network service. Using the parameters of the surface roughness and applied load, insertion loss of connector is measured. Due to scattering and change of refractive index, an optimal condition for low-loss coupling exists. We present the optimal condition as surface roughness $R_{rms}$ = 8 nm and contact load up to 50 N.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.61-68
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• 2006

This paper is to investigate the influence of the endface quality on the loss characteristics of a plastic optical fiber(POF) connector and the stability of new designed sleeve for in-car network service. Using the parameters of the surface roughness and applied load, insertion loss of connector is measured. Endface condition for optimizing the connection is presented by the surface roughness satisfying loss criteria and the stress for minimizing the loss, $R_{rms}=8nm$ and 19 MPa, respectively. By vibration test and dynamic loss measurement, we show the stability of the new designed sleeve.

• Journal of Biomedical Engineering Research
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• v.30 no.6
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• pp.489-494
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• 2009

In this study, we fabricated a plastic optical fiber based sensor which can monitor the respiration of a patient. The circumference changes of the abdomen were measured using a mirror, a light source and optical detectors because the circumferences of the abdomen could be varied with respiration. The intensity of the reflected lights were measured according to the changes of distance between mirror and plastic optical fiber connected to a light source and a photodiode-amplifier system using a Y-coupler. The respiration signals of fiber-optic sensor system were compared with those of the respiratory and temperature transducers of the $BIOPAC^{(R)}$ system. It is expected that a fiber-optic respiration sensor could be developed for real time respiration monitoring during MRI procedure based on this study.

• Journal of the Korean Solar Energy Society
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• v.22 no.3
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• pp.57-65
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• 2002

The photocatalytic degradation of TCE using solar energy in POFR was studied. The use of solar energy was investigated in plastic optica fiber photocatalytic reactor (POFR). In POFR, the main parameters of photocatalytic degradation of TCE were lihgt intensity, thickness of $TiO_2$-coated film on plastic fiber core, the same of total $TiO_2$-coated surface area with changed length. We studied the apparent photonic efficiency and photocatalytic degradation rate of TCE in POFR. The apparent photonic efficiency of various light intensities was decreased by an incresed intensities. The photocatalytic activities of $TiO_2$-coated optical fiber reactor system depended on the coating thickness, and total clad-stripped surface area of POF. Photocatalytic degradation of trichloroethylene ($C_2HCl_3$, TCE) in the gas-phase was elucidated by using $TiO_2$-coated plastic optical fiber reactor. In TCE degradation, in-situ FTIR measurement resulted in mineralization into $CO_2$.