• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.534-543
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• 2000

In this paper, when the current optical communication system is used for the DWDM. The FBG filter for the DWDN is able to reduce the interferences between the adjacent channels. In this paper, therefore, we find the relection spectrums for the three types of induced index changes, that is, uniform, Gaussian apodized, and raised-cosine apodized. From the obtained result in this paper, we can see that uniform FBG does not fit, and that the smaller the maximum induced index change $\sigma$ is and the larger the value of parameter C in the raised-cosine apodized FBG and G in the Gaussian apodized FBG are the fitter they are on the narrow filter for DWDM.

• Progress in Medical Physics
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• v.7 no.1
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• pp.25-35
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• 1996

Optical measurements of turbid biological tissue have provided a means to study tissue metabolism, tissue blood perfusion and blood oxygenation non-invasively. We used the red light of 660nm and infrared of 880nm to measure the blood fractional volume and oxygen saturation of biological tissue. In vivo reflectance data were obtained the physiological change from the deep tissue in human subject. The data evaluation was assessed by examining the slopes of the plotter index for the changes in oxygen saturation and blood fraction volume. The index is the natural logarithm of the ratio of reflected light intensity from measured medium to reference intensity at each wavelength. According to the experimental results, oxygen index changes significantly in the muscle of calf during exercise.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.4
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• pp.121-129
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• 2014

This study was carried out to develop an efficient plant growth system that can be controlled by altering the wavelength and illumination using a LED module. If it is possible to develop a system that can be controlled in this manner, utilizing different characteristics in the meaningful wavelength band depending on the growth time or type of plant, the plant growth conditions can be optimized. In order to this, red, green, blue and white LEDs are arrayed in a rectangle, consisting of LED modules which can be combined with each other. Consequently, the array can be used to select the optimal light conditions with monochromatic red, green, blue and white LEDs, or mixed LEDs, for plant growth. Experiments on the characteristics of the wavelengths to evaluate the efficiency of the plant growth system were performed. The usefulness of the system was demonstrated through a cultivation test involving several special plants.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.6
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• pp.51-60
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• 2004

In this paper, we optimized the PDT laser system to improve the therapy effects of malignancies. In order to optimize, the variation of laser output and specific wavelength shift have to reduced. To improve the PDT therapy clinician require the diverse radiation mode which irradiate the tumor surface. Continuous wave mode that general application may causes tissue thermal damage not only to tumor tissue, but also to normal tissue. In this paper, therefore, we suggested new technique for radiation method to improved PDT effects and prevented to the thermal effects for the tissue. In the experimental we verified the stability of wavelength, laser output stability and proved the reduced thermal effects to the tissue using the pulse & burst radiation modes in vitro.

• Korean Journal of Optics and Photonics
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• v.10 no.4
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• pp.328-334
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• 1999

Methylene blue-sensitized photopolymerizable material based on acrylamide is investigated with two-wave energy coupling experiments. Differently from other studies, self-diffraction oscillations are observed and the grating phase is determined without applying external electric fields, moving nonlinear materials, and phase shifting one of two writing beams. The phase grating showed a phase shift of $\pm$50$^{\circ}$ with respect to the intensity grating. Modified Kogelnik's coupled wave equation considering the mixed gratings of phase and absorption gratings and nonzero spatial phase shifts of the gratings with respect to the intensity interference patterns formed during the two-wave energy coupling is discussed in detail to understand these phenomenon.

• Journal of Marine Bioscience and Biotechnology
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• v.8 no.1
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• pp.24-29
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• 2016

Microalgae are considered as superior biodiesel producers, because they could effectively produce high amount of lipid with fast growth rate. In this study, Chlorella vulgaris was exposed to various light wavelengths (${\lambda}_{max}$ 470 nm, ${\lambda}_{max}$ 525 nm, and ${\lambda}_{max}$ 660 nm) using light emitting diodes (LEDs) to examine effect of light quality on their growth and fatty acid production in 0.4-L bubble column photobioreactors. Fluorescent lamps were also used as polychromatic light sources (control). From the results, biomass productivity was varied by light wavelength from 0.05 g/L/day to 0.30 g/L/day. Maximum biomass productivity was obtained from red LED among tested ones. We also observed that contents of oleic acid and linolenic acid, which affect biodiesel properties, were significantly changed depending on supplied wavelength. These results indicated that production of algal biomass, and fatty acid content and productivity could be improved or controlled by supplying specific light wavelength.

• Journal of the Korean Society of Safety
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• v.16 no.2
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• pp.121-129
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• 2001

This paper demonstrates the development of optical temperature sensor based on the etched planar waveguide Bragg grating. Topics include design and fabrication of the etched planar waveguide Bragg grating, investigation of the grating reflection characteristics, and temperature measurement capabilities. The typical bandwidth and reflectivity of the surface etched grating has been ~0.2nm and ~7%, respectively, at a wavelength of ～1552nm. The temperature-induced wavelength change of the optical sensor is found to be slightly non-linear over ～20$0^{\circ}C$ temperature range. Theoretical models for the grating response of the sensor based on waveguide and plate deformation theories agree with experiments to within acceptable tolerance.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.4
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• pp.367-374
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• 2004

In order for the measurement results of an electro-optical distance meter(EDM), which is widely used in surveying, to be reliable, an EDM should be calibrated. For the calibration of an EDM, we have settled a traceability chain, which connects the EDM under calibration to the definition of metre. The chain starts from the iodine stabilized He-Ne laser which realizes the definition of metre, and then connected to a stabilized laser interferometer, a standard EDM, and finally to the EDM under calibration through the baseline. We achieved the expanded calibration uncertainties of the scale and length measurement of an EDM being evaluated to be 6$\times$10$^{-6}$ and 0.2 mm, respectively. Two different calibration methods, and their results are compared.

• Journal of the Korea Society of Computer and Information
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• v.17 no.8
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• pp.51-60
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• 2012

I propose the 5Gbps/1.25Gbps WDM/TDM hybrid Passive Optical Network(PON) with inverse RZ(Return to Zero) code coded downstream and NRZ(Non Return to Zero) upstream re-modulation and analyze its performance by performing simulation with MATLAB. The results have shown that an optical line termination (OLT) can be connected to 8, 16 optical network unit (ONU)s with the Bit Error Rate(BER) of $10^{-9}$ when the distance between OLT and ONU is 10Km and transmitted optical powers are more than -3.8, -0.9dBm, respectively. The proposed WDM/TDM hybrid PON system can solve the problem of data rate limit in upstream which happened in the conventional TDM PON because the upstream data rate is proportional to ONU and does not require a light source in ONU and its control circuits in OLT, thus can be a useful technology for asymmetric optical subscriber networks.

• Journal of Chest Surgery
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• v.36 no.10
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• pp.794-797
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• 2003

Photodynamic therapy (PDT) is a local, endoscopically controlled nonoperative therapeutic technique based on selective sensitization of mucosal, malignant and precancerous lesions of the esophagus, trachea and bronchus prior to light-induced tissue destruction in the department of thoracic and cardiovascular surgery. PDT is effective and safe for palliative treatment of neoplasms in the stomach, esophagus, and lung. But skin phototoxicity is unsatisfactory, therefore optimization of management of post-PDT is necessary for preventing phototoxic side effects of skin. Careful patient education in photoprotection techniques, close patient follow-up, early dermatologic referral and medical treatment are recommended. We performed PDT in a patient with intrathoracic constructed stomach. We report this case with a brief review of literatures, therefore.