• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.6
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• pp.49-56
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• 2007

In this paper, the development of excitation light source is proposed for excitation light of the photodynamic therapy of cancer. Since the selection of the wavelength band of excitation light has an interrelation with fluorescence generation according to the selection of a photosensitizer. This study aims at designing and evaluating light source that can stably generate light with various kinds of wavelengths in order to make possible photodynamic diagnosis using a photosensitizer and diagnosis using auto-fluorescence. The light source device was a Xenon lamp and filter wheel, composed of an optical output control through iris and filters with several wavelength bands. It also makes the inducement of auto-fluorescence possible because it is designed to generate a wavelength band of 380-420nm, 430-480nm, 480-560nm. The transmission part of the light source was developed to enhance the efficiency of light transmission. To evaluate this light source device by KFDA#s technical reference, the characteristics of the light output and wavelength band were found.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.222-226
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• 2007

We suggest the fluorescence endoscope system that has light source apparatus providing selectable white or excitation light. White light source generates normal color images and is easily switched over to excitation light with the wide spectrum range from 380 nm to 580 nm. 5-ALA is deposited selectively in the abnormal tissue like cancer and causes fluorescence in the red spectrum range when excited by blue spectrum range. In addition, the others of excitation light make the color background image by reflected light to allow accurate orientation and visualization of the abnormal tissue and around. According to clinical studies, the fluorescence intensity contrast that defines the fluorescence intensity of lesion over the fluorescence intensity of around has more than 2 in tumour. Proposed system is useful and objective way in early diagnosis. Furthermore, it can be used in the biopsy for tumour classification at the highest fluorescence intensity point.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.6
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• pp.510-514
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• 2005

We have investigated the excitation-light source dependence of photo-catalytic efficiency for the benzene removal. The photo-catalytic module for the benzene removal is fabricated by a combination of GaN-based ultraviolet light-emitting diode (UV GaN-LED) and $TiO_2$ thin film coated on an aluminum plate. The benzene reduction rates of 365 nm and 375 nm modules at 60 mA junction current are approximately $8.95\;\%/Hr$ and $9.2\;\%/Hr$, respectively, which indicates that 365 nm GaN-LED is more effective than 375 nm GaN-LED. The benzene reduction efficiency is also noticeably dependent on the excitation wavelength and excitation-light power, as well as it is increased with the shorter wavelength and higher excitation power. This result exhibits that UV GaN-LED is useful to remove the volatile organic compounds (VOCs) existing in the environment.

• Journal of the Optical Society of Korea
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• v.17 no.1
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• pp.81-85
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• 2013

A miniaturized fluorescence detection system based on total internal reflection (TIR) configuration, which is applicable to detecting the presence of biological materials labeled with fluorescence dye in micro total analysis systems (${\mu}TAS$), is proposed. In conventional fluorescence testing and analysis devices, interference between the excitation light beam and the emitted light from dyes is unavoidable. This paper presents a fluorescence detection system based on TIR configuration that allows the excitation light beam and the emitted light to be spatially perpendicular to each other so as to minimize the interference where fluorescence emission is detected at the orthogonal angle to the excitation beam. We achieved the limit of detection of about 5 nmol/L with a high linearity of 0.994 over a wide range of 6-FAM mol concentration, being comparable to that in earlier studies.

• Journal of Photoscience
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• v.9 no.2
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• pp.359-361
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• 2002

A green mutant of Rhodobacter sphaeroides 60I was acquired by chemical induction. The blue-shifted of the carotenoid absorption was found in the Light-harvesting complex II (LH2) of the mutant. With the excitation at different wavelength, we observed that the evolution of excited-state dynamics in LH2 of Rhodobacter sphaeroides 60I. The dynamical traces demonstrate a dominant absorption followed concomitantly by an ultrafast transmission increase and decay with 818nm excitation.

• BMB Reports
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• v.40 no.5
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• pp.644-648
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• 2007

Exposure of algae or plants to irradiance from above the light saturation point of photosynthesis is known as high light stress. This high light stress induces various responses including photoinhibition of the photosynthetic apparatus. The degree of photoinhibition could be clearly determined by measuring the parameters such as absorption and fluorescence of chromoproteins. In cyanobacteria and red algae, most of the photosystem (PS) II associated light harvesting is performed by a membrane attached complex called the phycobilisome (PBS). The effects of high intensity light (1000-4000 ${\mu}mol$ photons $m^{-2}s^{-1}$) on excitation energy transfer from PBSs to PS II in a cyanobacterium Spirulina platensis were studied by measuring room temperature PC fluorescence emission spectra. High light (3000 ${\mu}mol$ photons $m^{-2}s^{-1}$) stress had a significant effect on PC fluorescence emission spectra. On the other hand, light stress induced an increase in the ratio of PC fluorescence intensity of PBS indicating that light stress inhibits excitation energy transfer from PBS to PS II. The high light treatment to 3000 ${\mu}mol$ photons $m^{-2}s^{-1}$ caused disappearance of 31.5 kDa linker polypeptide which is known to link PC discs together. In addition we observed the similar decrease in the other polypeptide contents. Our data concludes that the Spirulina cells upon light treatment causes alterations in the phycobiliproteins (PBPs) and affects the energy transfer process within the PBSs.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.19-31
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• 2005

During the last decade, the exploration of nanoscale device and circuitry based on molecules has gained increasing interest. In parallel with this, considerable effort is being devoted to the development of molecular photonic/electronic materials based on various porphyrin arrays. This involves light as an input/output signal and excitation energy migration as a mechanism for signal transmission. Absorption of a photon at the light collector end of the porphyrin array yields the excited state, which migrates among the intervening pigments until reaching the emitter, whereupon another photon is emitted. As a consequence, it is relevant to understand the excitation energy transfer (EET) processes occurring in various forms of porphyrin arrays for the applications as artificial light harvesting arrays and molecular photonic/electronic wires. Since the excitonic (dipole) and electronic (conjugation) couplings between the adjacent porphyrin moieties in porphyrin arrays govern the EET processes, we have characterized the EET rates of various forms of multiporphyrin arrays (linear, cyclic, and box) based on various time-resolved spectroscopic measurements. We believe that our observations provide a platform for further development of molecular photonic/electronic materials based on porphyrin arrays.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.73-76
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• 2007

Photodynamic diagnosis(PDD) is a method to diagnose the possibility of cancer, both by the principle that if a photosensitizer is injected into an organic tissue, it is accumulated in the tissue of a malignant tumor selectively after a specific period, and by a comparison of the intensity of the fluorescence of normal tissue with abnormal tissue after investigating the excitation light of a tissue with accumulated photosensitizer. Since the selection of the wavelength band of excitation light has an interrelation with fluorescence generation according to the selection of a photosencitizer, it plays an important role in POD. This study aims at designing and evaluating light source devices that can stably generate light with various kinds of wavelengths In order to make possible PDD using a photosensitizer and diagnosis using auto-fluorescence. The light source device was a Xenon lamp and filter wheel, composed of an optical output control through Iris and filters with several wavelength bands It also makes the inducement of auto-fluorescence possible because it is designed to generate a wavelength band of 380-400. The transmission part of the light source was, developed to enhance the efficiency of light transmission. To evaluate this light source device, the characteristics of the light output and wavelength band were verified. To validate the capability of this device as PDD the detection of auto-fluorescence using mouse was performed.

• Journal of the Korean Ceramic Society
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• v.37 no.2
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• pp.111-116
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• 2000

700nm red emission(3F3longrightarrow3H6) in Tm3+ ion with 800 nm(3H6longrightarrow3H4) excitation via upconversion process has been reported only in host materials which have low phonon energies such as halide crystals. However, we observed 700nm and 480nm(1G4longrightarrow3H6) upconverted emission with 800nm excitation in several oxide glasses which has never reported. With spectroscopic analyses and lifetime measurements of each nergy level of Tm3+ ion doped in various oxide glasses, following mechanisms are suggested. For red upconversion, upconversion mechanism changed with Tm3+ concentration. While direct excitation up to 3F3 level via anti-Stokes excitation was dominated at low concentration, two-step excitation via 3H6longrightarrow3H4 and 3F4longrightarrow3F3 transitions was dominated at high concentration. For blue upconversion, two step excitation mechanism up to 1G4 level was suggested as follows : electrons are exciated up to 3H5 with direct excitation with pumping light up to 3H4 followed by multiphonon relaxation, and then additional reabsorption of pumping light excites electrons up to 1G4.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.9 no.1
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• pp.35-41
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• 2023

Photodynamic therapy (PDT), in which a photosensitizer (PS), light, and molecular oxygen are essential components, is a non-invasive and highly effective cancer therapeutic method. However, PDT suffers from the penetration limit of light caused by attenuation and scattering of light through tissues constraining its use to skin and endoscopically accessible cancers. Cerenkov luminescence (CL) is defined as the light illuminated when charged particles move in a dielectric medium at a velocity greater than the phase velocity of light. It is known that medical radioisotopes in preclinical and clinical settings have enough energy to generate CL, and lately, CL has been exploited as an excitation source for PDT without external light illumination. This review introduces state of the art studies of radioisotope-based PDT for cancer, in which radioisotopes are utilized as a light source.