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Timeline of Joo Beom Eom

2018
Sep
01
Published new article




Article

Responsive alginate-cisplatin nanogels for selective imaging and combined chemo/radio therapy of proliferating macrophag...

Published: 01 September 2018 by AME Publishing Company in Quantitative Imaging in Medicine and Surgery

doi: 10.21037/qims.2018.09.01

Atherosclerosis is a major global health concern. Targeting macrophages is hypothesized as an alternative treatment for atherosclerosis. We synthesized alginate-based cisplatin-loaded nanogels (TANgel) as a pH-responsive drug-releasing theranostic nanoplatform for macrophage cells. Carboxylic acid groups of alginic acid were modified with iminodiacetic acid (IDA) to enhance chelation of platinum ions. The near infrared (NIR) fluorophore ATTO655 was conjugated to the modified alginic acid. Cisplatin was used as an antiproliferation drug and as a crosslinking agent between alginate molecules to form TANgel. Release behavior of cisplatin from TANgel was analyzed under different pH conditions. Cellular uptake and therapeutic efficacy of TANgel were tested in the macrophage cell line J774A.1 and normal human cell lines such as HDMVECn. The nanogel had a narrow size distribution of approximately 100 nm. The nanogel showed highly pH-responsive drug release behavior. All incorporated cisplatin was released at pH 5 within 48 h, while less than 15% was released at pH 7.4. The nanogel was preferentially taken up by J774A.1 cells compared to normal human cells, enabling selective NIR fluorescence imaging and chemotherapy of macrophage cells. In addition, the nanogel formulation lowered the therapeutic concentration of the drug with and without low dose radiation therapy (RT) compared to the free drug form. This nanogel system may have potential utility for selective NIR fluorescence imaging and combined chemo/radio therapy of proliferating macrophage cells in atherosclerotic regions, allowing for reduction of systemic toxicity.

0 Reads | 1 Citations
2018
Mar
14
Published new article




Article

Determination of organic compounds in water using ultraviolet LED

Published: 14 March 2018 by IOP Publishing in Measurement Science and Technology

doi: 10.1088/1361-6501/aaa364

In this paper, we demonstrate the detection of organic compounds in water by applying an ultraviolet LED (280 nm) spectroscopy system and photodetector. The LED spectroscopy system showed a high correlation between the prepared potassium hydrogen phthalate (KHP) concentration and that calculated by multiple linear regressions, indicating an adjusted coefficient of determination from 0.953 to 0.993. In addition, a comparison between the spectroscopy system and total organic carbon analyzer indicated that the concentration differences were small. Based on the close correlation between the spectroscopy and photodetector absorbance values, organic measurement with photodetector could be configured for monitoring.

4 Reads | 0 Citations
2017
Aug
23
Published new article






A three-dimensional scanning apparatus based on structured illumination method and its application in dental scanning

Published: 23 August 2017 by SPIE-Intl Soc Optical Eng in Applied Optical Metrology II

doi: 10.1117/12.2271018

1 Reads | 0 Citations
2017
Jul
15
Published new article




Article

Development of Three-Dimensional Dental Scanning Apparatus Using Structured Illumination

Published: 15 July 2017 by MDPI in Sensors

doi: 10.3390/s17071634

We demonstrated a three-dimensional (3D) dental scanning apparatus based on structured illumination. A liquid lens was used for tuning focus and a piezomotor stage was used for the shift of structured light. A simple algorithm, which detects intensity modulation, was used to perform optical sectioning with structured illumination. We reconstructed a 3D point cloud, which represents the 3D coordinates of the digitized surface of a dental gypsum cast by piling up sectioned images. We performed 3D registration of an individual 3D point cloud, which includes alignment and merging the 3D point clouds to exhibit a 3D model of the dental cast.

4 Reads | 3 Citations
2017
Feb
06
Published new article




Article

Terahertz transmission properties of silicon wafers using continuous-wave terahertz spectroscopy

Published: 06 February 2017 by IOP Publishing in Measurement Science and Technology

doi: 10.1088/1361-6501/aa57e5

2 Reads | 0 Citations
2017
Jan
01
Published new article




Article

Continuous wave terahertz spectroscopy system with stably tunable beat source using optical switch

Published: 01 January 2017 by Elsevier BV in Optics Communications

doi: 10.1016/j.optcom.2016.08.067

2 Reads | 3 Citations
2016
Nov
26
Published new article






LED Optical Sensor System for the Detection of Water Pollutant

Published: 26 November 2016 by Science and Engineering Research Support Society in Electrics, Electronics, and Computer Science 2016

doi: 10.14257/astl.2016.139.82

3 Reads | 0 Citations
2016
Jan
04
Published new article




Article

Detection of Organic Compounds in Water by an Optical Absorbance Method

Published: 04 January 2016 by MDPI in Sensors

doi: 10.3390/s16010061

This paper proposes an optical method which allows determination of the organic compound concentration in water by measurement of the UV (ultraviolet) absorption at a wavelength of 250 nm~300 nm. The UV absorbance was analyzed by means of a multiple linear regression model for estimation of the total organic carbon contents in water, which showed a close correlation with the UV absorbance, demonstrating a high adjusted coefficient of determination, 0.997. The comparison of the TOC (total organic carbon) concentrations for real samples (tab water, sea, and river) calculated from the UV absorbance spectra, and those measured by a conventional TOC analyzer indicates that the higher the TOC value the better the agreement. This UV absorbance method can be easily configured for real-time monitoring water pollution, and built into a compact system applicable to industry areas.

0 Reads | 2 Citations
2015
Feb
27
Published new article






LED absorption sensor system for the detection of organics in water

Published: 27 February 2015 by SPIE-Intl Soc Optical Eng in Integrated Optics: Devices, Materials, and Technologies XIX

doi: 10.1117/12.2081350

Determination of Organic compound concentration in water – is an imperative key to the control of water quality since it provide important information on pollution control of water supply. This work propose an optical sensor system where the organic compound concentration in water is determined using LED light(280nm). The absorbance was quantified according to the high, low and fine concentration of organic compound by means of linear regression modeling. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

0 Reads | 0 Citations
2015
Jan
01
Published new article






Thermal stability improvement of the optical probe which uses LEDs as an optical source

Published: 01 January 2015 by The Optical Society in Optics in the Life Sciences

doi: 10.1364/boda.2015.jt3a.13

0 Reads | 0 Citations
2013
Jun
01
Published new article






Optical fiber sensor for refractive index measurement based on localized surface plasmon resonance

Published: 01 June 2013 by Institute of Electrical and Electronics Engineers (IEEE) in 2013 Conference on Lasers and Electro-Optics Pacific Rim (CLEOPR)

doi: 10.1109/cleopr.2013.6600584

Fiber-optic based localized surface plasmon sensor has been developed for the measurements of refractive index (RI). The RI sensitivity of 506 nm/RI unit was achieved.

0 Reads | 0 Citations
2012
Oct
17
Published new article






Overcoupled bending insensitive holey optical fiber coupler

Published: 17 October 2012 by SPIE-Intl Soc Optical Eng in OFS2012 22nd International Conference on Optical Fiber Sensors

doi: 10.1117/12.975130

A holey optical fiber (HOF) wavelength division multiplexing (WDM) coupler, which divides optical waves according to their wavelengths, has been made by using the Fused Biconical Tapered (FBT) method. The transmission band of the proposing HOF WDM coupler could be easily tuned by adjusting the pulling length during the FBT process. The HOF used for the WDM coupler was designed to be bending insensitive, which could withstand a bending radius of up to 6 mm. Interestingly, it was observed that the air hole structure of the HOF should be maintained to have the property of a WDM coupler. The cross sectional SEM images of the implemented HOF WDM coupler are presented along with the light intensity distribution at the coupling region. The proposed HOF couplers may find applications as optical CWDM (coarse wavelength division multiplexing) filters and as optical fiber sensors also.

0 Reads | 1 Citations
2012
Feb
23
Published new article




Article

Interferometric Fiber Optic Sensors

Published: 23 February 2012 by MDPI in Sensors

doi: 10.3390/s120302467

Fiber optic interferometers to sense various physical parameters including temperature, strain, pressure, and refractive index have been widely investigated. They can be categorized into four types: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac. In this paper, each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields. Some specific examples of recently reported interferometeric sensor technologies are presented in detail to show their large potential in practical applications. Some of the simple to fabricate but exceedingly effective Fabry-Perot interferometers, implemented in both extrinsic and intrinsic structures, are discussed. Also, a wide variety of Mach-Zehnder and Michelson interferometric sensors based on photonic crystal fibers are introduced along with their remarkable sensing performances. Finally, the simultaneous multi-parameter sensing capability of a pair of long period fiber grating (LPG) is presented in two types of structures; one is the Mach-Zehnder interferometer formed in a double cladding fiber and the other is the highly sensitive Sagnac interferometer cascaded with an LPG pair.

4 Reads | 95 Citations
2011
Sep
12
Published new article




Article

Compact and multiplexible hydrogen gas sensor assisted by self-referencing technique.

Published: 12 September 2011 in Optics Express

doi:

We have experimentally implemented a multiplexible but compact fiber sensor system suitable for multipoint sensing of hydrogen gas leakage. By making dual cavities along an optical fiber and coating a palladium film only at the end of the fiber tip, the measurement errors induced by the optical source power fluctuation and the mechanical perturbation in the lead fiber could be compensated. By adjusting the length of the dual-cavity, the capability of multiplexing several hydrogen sensors could be achieved. The experiment results showed that the response speed of the sensor was increasing with temperature, but at a low temperature the response amplitude became large.

0 Reads | 0 Citations
2011
Sep
01
Published new article




Article

Compact and multiplexible hydrogen gas sensor assisted by self-referencing technique

Published: 01 September 2011 by The Optical Society in Optics Express

doi: 10.1364/oe.19.018190

We have experimentally implemented a multiplexible but compact fiber sensor system suitable for multipoint sensing of hydrogen gas leakage. By making dual cavities along an optical fiber and coating a palladium film only at the end of the fiber tip, the measurement errors induced by the optical source power fluctuation and the mechanical perturbation in the lead fiber could be compensated. By adjusting the length of the dual-cavity, the capability of multiplexing several hydrogen sensors could be achieved. The experiment results showed that the response speed of the sensor was increasing with temperature, but at a low temperature the response amplitude became large.

0 Reads | 7 Citations
2011
May
15
Published new article






Characteristics of hydrogen gas sensor based on a wavelength division multiplexing fiber coupler

Published: 15 May 2011 by SPIE-Intl Soc Optical Eng in 21st International Conference on Optical Fiber Sensors

doi: 10.1117/12.885182

A fiber optic sensor based on the wavelength division multiplexer coated with a palladium (Pd) thin film is designed for hydrogen gas detection. The sensing mechanism of this sensor is measuring the wavelength shift that is induced by the evanescent field interaction with the refractive index change of Pd film when it absorbs hydrogen.

0 Reads | 0 Citations
2011
Feb
10
Published new article






2x2 photonic crystal fiber splitter for 800 nm spectral domain optical coherence tomography

Published: 10 February 2011 by SPIE-Intl Soc Optical Eng in SPIE OPTO

doi: 10.1117/12.875034

We report the fabrication and performance of the 2x2 photonic crystal fiber (PCF) splitter that was designed as a single mode splitter at the 800 nm optical band and used as the beam splitter for a spectral domain optical coherence tomography system. The PCF splitter has been made by coupling PCFs to a planar lightwave circuit (PLC) splitter chip. The PLC splitter chip was fabricated to have a single mode property at the 800 nm wavelength band and the PCFs were securely connected to the PLC chip through PCF block arrays having lithographically fabricated V grooves. The core size of the splitter chip was about 5 μmx5 μm and the core-cladding index difference was about 0.15 %. With the implemented PCF PLC splitter, we have obtained a low excess loss of 1.2 dB at 850 nm and a low polarization-dependent loss of 0.19 dB. With the proposed 2x2 PCF splitter, optical coherence tomography images of pearls were successfully obtained.

4 Reads | 0 Citations
2010
Dec
25
Published new article




Article

Specialty Fiber Coupler: Fabrications and Applications

Published: 25 December 2010 by Korean Journal of Optics and Photonics in Journal of the Optical Society of Korea

doi: 10.3807/josk.2010.14.4.326

0 Reads | 3 Citations
2010
Aug
15
Published new article




Article

Wavelength-division-multiplexing fiber coupler based on bending-insensitive holey optical fiber.

Published: 15 August 2010 in Optics Letters

doi:

A wavelength-division-multiplexing (WDM) coupler has been made with a bending-insensitive holey optical fiber (HOF) by using the fused biconical tapered (FBT) method. The transmission band of the proposed HOF WDM coupler could be easily tuned by adjusting the pulling length during the FBT process. Interestingly, it was observed that the air-hole structure of the HOF should be maintained to have the property of a WDM coupler. As the air holes collapse, the HOF WDM exhibits high-pass-filter-like properties. The cross-sectional scanning electron microscope images of the implemented HOF WDM coupler are presented along with the light intensity distribution measured at the coupling region of the coupler. The proposed HOF couplers may also find applications in optical coarse WDM systems and optical fiber sensors.

0 Reads | 0 Citations
2010
Aug
10
Published new article




Article

Wavelength-division-multiplexing fiber coupler based on bending-insensitive holey optical fiber

Published: 10 August 2010 by The Optical Society in Optics Letters

doi: 10.1364/ol.35.002726

A wavelength-division-multiplexing (WDM) coupler has been made with a bending-insensitive holey optical fiber (HOF) by using the fused biconical tapered (FBT) method. The transmission band of the proposed HOF WDM coupler could be easily tuned by adjusting the pulling length during the FBT process. Interestingly, it was observed that the air-hole structure of the HOF should be maintained to have the property of a WDM coupler. As the air holes collapse, the HOF WDM exhibits high-pass-filter-like properties. The cross-sectional scanning electron microscope images of the implemented HOF WDM coupler are presented along with the light intensity distribution measured at the coupling region of the coupler. The proposed HOF couplers may also find applications in optical coarse WDM systems and optical fiber sensors.

2 Reads | 2 Citations
2009
Dec
01
Published new article




Article

2x2 photonic crystal fiber splitter based on silica-based planar lightwave circuits.

Published: 01 December 2009 in Optics Letters

doi:

A 2x2 photonic crystal fiber (PCF) planar lightwave circuit (PLC) splitter, which splits optical power between two PCF channels, has been made by PCF-to-PLC connections. PCF array blocks were lithographically fabricated to have fiber V grooves and used to firmly hold PCFs and align them to the PLC splitter. The proposed splitter showed a rather flat splitting ratio over a wide wavelength range from 1250 nmto1750 nm. With the implemented splitter, we obtained a low excess loss of 1.6 dB, a low polarization-dependent loss of 0.1 dB, and a high return loss of 52 dB. The ultrabroadband operation of the proposed splitter is expected to find applications in optical performance monitoring, Ethernet passive optical networks, and biomedical optics including optical coherence tomography.

0 Reads | 0 Citations
2009
Nov
30
Published new article




Article

2×2 photonic crystal fiber splitter based on silica-based planar lightwave circuits

Published: 30 November 2009 by The Optical Society in Optics Letters

doi: 10.1364/ol.34.003737

A 2×2 photonic crystal fiber (PCF) planar lightwave circuit (PLC) splitter, which splits optical power between two PCF channels, has been made by PCF-to-PLC connections. PCF array blocks were lithographically fabricated to have fiber V grooves and used to firmly hold PCFs and align them to the PLC splitter. The proposed splitter showed a rather flat splitting ratio over a wide wavelength range from 1250 nmto1750 nm. With the implemented splitter, we obtained a low excess loss of 1.6 dB, a low polarization-dependent loss of 0.1 dB, and a high return loss of 52 dB. The ultrabroadband operation of the proposed splitter is expected to find applications in optical performance monitoring, Ethernet passive optical networks, and biomedical optics including optical coherence tomography.

0 Reads | 1 Citations
2003
Jul
07
Published new article






Microbending-induced loss of a photonic crystal fiber

Published: 07 July 2003 by SPIE-Intl Soc Optical Eng in Photonic Crystal Materials and Devices

doi: 10.1117/12.479812

It is reported that the spectral loss of a photonic crystal fiber having a large hole-to-hole distance (~10 micron) is sensitive to micro- and macrobending on the fiber. For the macrobending experiment, the fiber was simply wound round a circular structure of known radius, which was reduced up to a few centimeters. As the bending radius was decreased, the transmission loss was increased. In terms of wavelength, the spectral loss was rather flat, which looked suitable for a wide-band fiber attenuator. For the microbending case, a series of regularly spaced silica rods was attached on a slide glass and pressed against the fiber by loading a series of metal plates of known mass on the glass. With this scheme, it was possible to induce periodic microbending on the photonic crystal fiber. The silica rods had the same diameter of a few hundred microns and spaced by about 500 micron. The bending loss was increased by adding the weight. The photonic crystal fiber having a large hole-to-hole distance was found to be highly sensitive to both microbending and macrobending when compared to the conventional single-mode fiber. In this paper, we will discuss the microbending effect on the photonic crystal fiber with various experimental conditions, such as the periodicity and the length of the microbend-inducing region.

2 Reads | 0 Citations
2003
Jun
01
Published new article




Article

Dependence of the Transmission Characteristics of Photonic Crystal Fiber on the Macrobending Radius and the Mechanically...

Published: 01 June 2003 by Korean Journal of Optics and Photonics in Journal of the Optical Society of Korea

doi: 10.3807/josk.2003.7.2.072

0 Reads | 0 Citations
2003
Jun
01
Published new article




Article

The Fabrication of a Photonic Crystal Fiber and Measurement of its Properties

Published: 01 June 2003 by Korean Journal of Optics and Photonics in Journal of the Optical Society of Korea

doi: 10.3807/josk.2003.7.2.079

0 Reads | 0 Citations
2002
May
15
Published new article




Article

Photonic crystal fiber coupler

Published: 15 May 2002 by The Optical Society in Optics Letters

doi: 10.1364/ol.27.000812

Fiber couplers made with photonic crystal fibers (PCF) are reported. Two types of PCF were fabricated by means of stacking a group of silica tubes around a silica rod and drawing them. The fiber couplers were made by use of the fused biconical tapered method. With a fiber that had five hexagonally stacked layers of air holes, a 33/67 coupling ratio was obtained, and with a one-layer four-hole fiber, a 48/52 coupling ratio was obtained. The fabrication processes and the characteristics of the PCFs and the PCF couplers are presented.

2 Reads | 11 Citations
2002
May
15
Published new article




Article

Photonic crystal fiber coupler.

Published: 15 May 2002 in Optics Letters

doi:

Fiber couplers made with photonic crystal fibers (PCF) are reported. Two types of PCF were fabricated by means of stacking a group of silica tubes around a silica rod and drawing them. The fiber couplers were made by use of the fused biconical tapered method. With a fiber that had five hexagonally stacked layers of air holes, a 33/67 coupling ratio was obtained, and with a one-layer four-hole fiber, a 48/52 coupling ratio was obtained. The fabrication processes and the characteristics of the PCFs and the PCF couplers are presented.

0 Reads | 0 Citations
2002
Apr
26
Published new article






Optical properties measurement of several photonic crystal fibers

Published: 26 April 2002 by SPIE-Intl Soc Optical Eng in Photonic Bandgap Materials and Devices

doi: 10.1117/12.463867

We report the fabrication process for several types of photonic crystal fibers (PCFs), which enables mass-production with a 125micrometers diameter. Five layers of silica capillary tubes having 2 mm inner and 3 mm outer diameters were stacked in a hexagonal pattern around a silica rod of a 3 mm diameter. By jacketing a large silica tube around the tube stack, the preform for a PCF was obtained. Another type of PCF was made by stacking four tubes in one layer, which had 6 mm inner and 8 mm outer diameters. In order to draw PCFs from both types of preforms, a drawing tower for conventional fibers was used. In the beginning of the drawing process, the temperature was set to be the running temperature for the conventional fiber, and then lowered by a couple of hundreds degrees. The optical properties of the fabricated PCFs were measured with various hole sizes and pitches. These include the intensity distribution of the guided beam that was a single mode at 1550 nm, and the transmission loss measured by using the cut back method, and the fundamental mode cut-off characteristic at a short wavelength, and the numerical aperture measured at several wavelengths by using the far field patterns.

0 Reads | 0 Citations
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