• Journal of the Korea Society of Computer and Information
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• v.4 no.1
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• pp.15-20
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• 1999

In this paper, we propose some essential requirements for CBM(Computer Based Multimedia) based distance education. This is a class of multimedia distance education in which the multimedia technique is combined with the distance home education application that is real time collaborative application on cyber-space using the information super highway. Requirements in this paper is observed standard at ITU(International Telecommunication Union). international standardization organization for multimedia communication. And. a structure for integrated home information service on the information super highway is based on IEEE 1394 serial communication and POF(Plastic Optical Fiber) home backbone that is study for application service according to the multimedia based distance home study system.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.709-715
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• 2011

Chattering in cutting operations are usually a cumbersome part of the manufacturing process in mechanical. Particular, machining performance such as that of the boring process is limited by cutting condition at the movable components. Among various sources of chatter vibration, detrimental point in cutting condition is found a mechanical condition on overhang. It limits cutting speed, depth, surface roughness and tool wear failure as result because the all properties are varying with the metal removal process. In this case, we have to observe the resonance frequencies of a boring bar for continuous cutting. In the established research, boring bar vibration of cutting system has been measured with the aid of accelerometer. However, the inherent parameters of internal turning operations are severely limit for the real time monitoring on accelerometers. At this point, this paper is proposed other method for real time monitoring during continuous cutting with optical fiber at the inside of boring bar. This method has been used a plastic fiber in the special jig on boring bar by based on experimental modal analysis. In this study, improvement of monitoring system on continuous internal cutting was attempted using optical fiber sensor of inside type because usually chattering is investigated experimentally measuring the variation in chip thickness. It is demonstrated that the optical fiber sensor is possibility to measure of chattering with real time in boring process.

• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.343-346
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• 2003

본 연구에서는 IPA(isopropyl alcohol)를 분해물질로 선정하여 플라스틱 광섬유(Pastic Optical Fiber, POF)에 TiO₂를 코팅하여 오염물질을 분해하였다. P-25가 코팅된 POF의 표면은 유기계, 무기계, 유ㆍ무기 바인더를 사용한 것 모두 깨끗하였고, 무기계 바인더를 사용하여 코팅한 POF는 부착력이 현저히 떨어졌다. IPA 분해 결과, 무기계 바인더를 사용한 경우, 다른 종류의 바인더와는 다르게 IPA의 초기농도 값이 매우 작게나왔는데 이러한 결과는 반응기에 주입된 IPA가 평형이 될 때까지 기다리는 동안 흡착이 일어났기 때문으로 생각된다. 유기계 바인더를 사용하여 코팅한 POF는 IPA 분해 효율이 매우 저조하였고 유ㆍ무기 바인더를 사용하여 코팅한 POF의 IPA 분해 효율은 우수하였다. P-25와 IPA의 분해 효율이 우수한 유ㆍ무기 바인더의 비율을 10 : 10 : 8, 10 : 6, 10 : 4, 10 : 2로 바꾸어 IPA를 분해한 결과, P-25와 유ㆍ무기 바인더의 비율이 10 : 2일 때 IPA 분해 효율이 가장 우수하였다. 또한 P-25와 코팅액 제조 시 회석제로 사용되는 에탄올의 질량비를 1 : 7, 1 : 11, 1 : 15로 바꾸어 IPA를 분해한 결과, P-25와 에탄올의 비율이 1 : 15 일 때 IPA 분해 효율이 가장 우수하였다.

• Korean Journal of Optics and Photonics
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• v.24 no.4
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• pp.196-200
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• 2013

Heretofore, it was enough that most of optical transceiver modules for automotive networks have the performance of data rate from 10 Mbps to 150 Mbps. As the required data rate in automotive infotainment systems has recently been increasing, the development of a new optical transceiver having high speed data rate over 1Gbps is now required. Therefore, we suggested a next-generation bi-directional optical transceiver module using vertical cavity surface emitting laser technology and plastic clad fiber technology, for the next-generation automotive optical network, MOST1000. We fabricated the high-speed and compact optical transceiver having 1 Gbps data rate and -22 dBm sensitivity satisfying bit error rate $10^{-12}$.

• Journal of Sensor Science and Technology
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• v.17 no.6
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• pp.462-469
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• 2008

In this study, we have fabricated a fiber-optic radiation sensor using an organic scintillator and plastic optical fiber for brachytherapy dosimetry. Also, we have measured relative depth dose rates of Ir-192 source using a fiber-optic sensor and compared them with the results obtained using a conventional EBT film. Cerenkov lights which can be a noise in measuring scintillating light with a fiber-optic sensor are measured and eliminated by using of a background optical fiber. It is expected that a fiber-optic radiation sensor can be used in brachytherapy dosimetry due to its advantages such as a low cost, simple usage and a small volume.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.2
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• pp.130-137
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• 2016

Non-destructive testing methods for composite materials (e.g., carbon fiber-reinforced and glass fiber-reinforced plastic) have been widely used to detect damage in the overall industry. This study detects defects using optical infrared thermography. The transient heat transport in a solid body is characterized by two dynamic quantities, namely, thermal diffusivity and thermal effusivity. The first quantity describes the speed with thermal energy diffuses through a material, whereas the second one represents a type of thermal inertia. The defect detection rate is increased by utilizing a lock-in method and performing a comparison of the defect detection rates. The comparison is conducted by dividing the irradiation method into reflection and transmission methods and the irradiation time into 50 mHz and 100 mHz. The experimental results show that detecting defects at 50 mHz is easy using the transmission method. This result implies that low-frequency thermal waves penetrate a material deeper than the high-frequency waves.

• Journal of Radiation Protection and Research
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• v.41 no.2
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• pp.105-109
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• 2016

Background: For an accelerator-based BNCT, we have fabricated a new detector consisting of quartz optical fibers that have excellent radiation-resistant characteristics. Materials and Methods: The developed detectors were irradiated at Kyoto University Research Reactor. Results and Discussion: The experimental results showed that the new detector had good output linearity for the neutron intensity, and the response of the new detector did not decrease during the irradiation. Conclusion: The new detector consisting of quartz optical fibers can be applied to measurement of neutron field of an accelerator-based BNCT.

• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.350-352
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• 2003

In this study plastic optical fibers(POFs) were considered as light-transmitting media and substrates for the potential use in photocatalytic environmental purification system. After the characteristics of POFs in terms of light transmittance and absorption were determined at the beginning, the detailed investigation was further performed through the photocatalytic degradation of trichloroethylene(TCE), iso-propanol and etc. with TiO$_2$-coated optical fiber reactor systems(POFR). It is concluded that the use of POfs is preferred to quartz optical fibers(QOFs) since the advantages such as ease of handling, lower cost, relatively reasonable light attenuation at the wavelength of near 400nm can be obtained. Various geometrical reactor shapes have been constructed and applied for the last one and half years. For the use of POF in water phase treatment, however, more detailed scientific and engineering aspects should be envisaged. This case requires a suitable mixture to obtain more stable and innocuous immobilization of photocatalyst on POF.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.244-247
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• 2002

We examined a possibility to use inorganic plastic scintillator, which has the effective atomic number close to that of human soft tissue, for the measurement of dose distributions in a shorter time period. The method was to irradiate a block of plastic scintillator as a phantom, and to measure the distribution of the scintillation light by a wave length analyzer through a thread of plastic optical fiber. By irradiating the diagnostic x-ray, we observed the emission spectrum of the scintillation light from the scintillator. It showed a peak at around 420nm with a full width of 140 nm. The emission spectrum was integrated to determine the total number of photons. The dependences of the amount of photons on the irradiated dose were measured. The results of the experiment show that the amount of emission light is in proportional to the irradiated dose. From this fact, we conclude that the present method can be used for the measurement of the depth dose distribution of the diagnostic x-rays.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.558-564
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• 2009

POF(Polymer optical fiber) offers advantages of lighter, inexpensive, and easier to use over GOF(glass optical fiber). Its higher transmission loss and low bandwidth, however, make it suitable only for short distance networking such as LAN. The polymer materials and its synthesis technology of low transmission loss and the broader application for flexible POF are the two of many critical areas to be investigated more. In the current study, low-noise POF modules are developed and optimized with a low noise amplifier and low cost LED of 650 nm. In order to demonstrate the dynamic characteristics of the POF module for optical communication and sensing, we have built an image transfer module, optical transmission speed measurement module, optical transceiver for RS-232, and sound-transfer module, and the signal characteristics of them are evaluated. It is found that the module can be readily used for a quick and simple measurement of optical transfer speed. With help of analog amplifier, LED, and PD, sound and image transfers through a maximum 60 m optical waveguide have been confirmed. Real-time data transfer was also demonstrated in PID control, which is thought to be valuable to industrial plant design and control.