1. Articles from Jeehyun Kim

    1-24 of 74 1 2 3 »
    1. Non-invasive optical screening of Streptococcus Pneumonia based inflammatory changes of the tympanic membrane and mastoid mucosa in guinea pig otitis media using optical coherence tomography

      Non-invasive optical screening of Streptococcus Pneumonia based inflammatory changes of the tympanic membrane and mastoid mucosa in guinea pig otitis media using optical coherence tomography

      Abstract: The accurate screening of otitis media (OM) lies in clarifying the numerous confounding and quantitative factors that are discovered during primary inspections. Increased awareness about bacterial biofilms and inflammation has allowed researchers to develop a better understanding of the bacterial infections that occur in the middle ear. In this study, four live guinea pigs were inoculated with Streptococcus pneumonia to induce OM-related inflammatory changes. Since optical techniques have been effectively used for diagnosis in medicine, low-coherence interferometry-based optical coherence tomography (OCT) was employed for depth-resolved high-resolution data screening. Multiple locations of the tympanic membrane (TM), mastoid mucosa, and round ...

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    2. Assessment of the Inner Surface Roughness of 3D Printed Dental Crowns via Optical Coherence Tomography Using a Roughness Quantification Algorithm

      Assessment of the Inner Surface Roughness of 3D Printed Dental Crowns via Optical Coherence Tomography Using a Roughness Quantification Algorithm

      Abstract: Dental crowns are used to restore decayed or chipped teeth, where their surfaces play a key role in this restoration process, as they affect the fitting and stable bonding of the prostheses. The surface texture of crowns can interfere with this restoration process, therefore the measurement of their inner surface roughness is very important but difficult to achieve using conventional imaging methods. In this study, the inner surfaces of dental crowns were three-dimensionally (3D) visualized using swept-source optical coherence tomography (SS-OCT) system. Nine crowns were fabricated with a commercial 3D printer using three different hatching methods (one-way, cross, and ...

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    3. Dynamic compensation of path length difference in optical coherence tomography by an automatic temperature control system of optical fiber

      Dynamic compensation of path length difference in optical coherence tomography by an automatic temperature control system of optical fiber

      Optical fiber is widely used in optical coherence tomography (OCT) to propagate light precisely with low attenuation and low dispersion. However, the total optical path length within the optical fiber varies in accordance with changes of the temperature. This leads changes in the total optical travel path of the interfering signals and results in shifting of OCT image position to an unintended depth pixel value. In this paper, we presented the temperature-based automatic path length compensating method in OCT to limit the external temperature effect and control the image position in micro-scale without manual movement of optical components. By utilizing ...

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    4. Optical Interferometric Fringe Pattern-Incorporated Spectrum Calibration Technique for Enhanced Sensitivity of Spectral Domain Optical Coherence Tomography

      Optical Interferometric Fringe Pattern-Incorporated Spectrum Calibration Technique for Enhanced Sensitivity of Spectral Domain Optical Coherence Tomography

      Depth-visualizing sensitivity can be degraded due to imperfect optical alignment and non-equidistant distribution of optical signals in the pixel array, which requires a measurement of the re-sampling process. To enhance this depth-visualizing sensitivity, reference and sample arm-channeled spectra corresponding to different depths using mirrors were obtained to calibrate the spectrum sampling prior to Fourier transformation. During the process, eight interferogram patterns corresponding to point spread function (PSF) signals at eight optical path length differences were acquired. To calibrate the spectrum, generated intensity points of the original interferogram were re-indexed towards a maximum intensity range, and these interferogram re-indexing points were ...

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    5. Identification of multi-dimensional thread geometry using depth-resolved swept-source optical coherence tomography for assessment of dental implant fabrication

      Identification of multi-dimensional thread geometry using depth-resolved swept-source optical coherence tomography for assessment of dental implant fabrication

      The geometrical characteristics of dental implants, such as thread depth and width, facing angle, pitch, and surface roughness, are important to assess their stability and osseointegration after implant surgery. Herein, we demonstrate the potential use of depth-resolved swept-source optical coherence tomography (SS-OCT) to assess the structural quality of widely used dental implants. The implemented SS-OCT system was centered at a wavelength of 1300 nm with a 100 nm full-width at half-maximum. Four dental implants with different structural formations fabricated using either titanium or ceramic were visualized. Qualitative assessments were performed using boundary flattening with an amplitude-profiling algorithm to emphasize and ...

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    6. Measurement of Vibrating Tympanic Membrane in an In Vivo Mouse Model Using Doppler Optical Coherence Tomography

      Measurement of Vibrating Tympanic Membrane in an In Vivo Mouse Model Using Doppler Optical Coherence Tomography

      Optical coherence tomography (OCT) has a micro-resolution with a penetration depth of about 2 mm and field of view of about 10 mm. This makes OCT well suited for analyzing the anatomical and internal structural assessment of the middle ear. To study the vibratory motion of the tympanic membrane (TM) and its internal structure, we developed a phase-resolved Doppler OCT system using Kasai’s autocorrelation algorithm. Doppler optical coherence tomography is a powerful imaging tool which can offer the micro-vibratory measurement of the tympanic membrane and obtain the micrometer-resolved cross-sectional images of the sample in real-time. To observe the relative ...

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    7. Non-Invasive Morphological Characterization of Rice Leaf Bulliform and Aerenchyma Cellular Regions Using Low Coherence Interferometry

      Non-Invasive Morphological Characterization of Rice Leaf Bulliform and Aerenchyma Cellular Regions Using Low Coherence Interferometry

      Non-invasive investigation of rice leaf specimens to characterize the morphological formation and particular structural information that is beneficial for agricultural perspective was demonstrated using a low coherence interferometric method called swept source optical coherence tomography (SS-OCT). The acquired results non-invasively revealed morphological properties of rice leaf, such as bulliform cells; aerenchyma, parenchyma, and collenchyma layer; and vascular bundle. Beside aforementioned morphologic characteristics, several leaf characteristics associated with cytological mechanisms of leaf rolling (leaf inclination) were examined for the pre-identification of inevitable necrosis and atrophy of leaf tissues by evaluating acute angle information, such as angular characteristics of the external bi-directional ...

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    8. Analysis of Enamel Loss by Prophylaxis and Etching Treatment in Human Tooth Using Optical Coherence Tomography: An In Vitro Study

      Analysis of Enamel Loss by Prophylaxis and Etching Treatment in Human Tooth Using Optical Coherence Tomography: An In Vitro Study

      Bonding of braces is an essential part in contemporary orthodontic treatment. For the proper strength of bracket bonding, enamel conditioning or surface treatment on tooth surface is required. Treatment on the tooth surface such as prophylaxis smoothing with pumice and enamel etching results in considerable damages to the enamel surface of the tooth. In this study, we have proposed optical coherence tomography as a noninvasive imaging technique for the evaluation of damage induced during such treatment procedures. Using depth intensity analysis of the obtained cross-sectional images, the damage resulting to the enamel surface was studied after prophylaxis smoothening and etching ...

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    9. 3-Dimensional characterization of cortical bone microdamage following placement of orthodontic microimplants using Optical Coherence Tomography

      3-Dimensional characterization of cortical bone microdamage following placement of orthodontic microimplants using Optical Coherence Tomography

      Microimplants are being used extensively in clinical practice to achieve absolute anchorage. Success of microimplant mainly depend on its primary stability onto the cortical bone surface and the associated Microdamage of the cortical bone during insertion procedure leads to many a microimplants to fail and dislodge from the cortical bone leading to its failure. Even though, previous studies showed occurrence of microdamage in the cortical bone, they were mainly 2-dimension studies or studies that were invasive to the host. In the present study, we used a non-invasive, non-ionizing imaging technique- Optical Coherence Tomography (OCT), to image and analyze the presence ...

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    10. Clinical Utility of Intraoperative Tympanomastoidectomy Assessment Using a Surgical Microscope Integrated with an Optical Coherence Tomography

      Clinical Utility of Intraoperative Tympanomastoidectomy Assessment Using a Surgical Microscope Integrated with an Optical Coherence Tomography

      Significant technical and optical advances are required for intraoperative optical coherence tomography (OCT) to be utilized during otological surgeries. Integrating OCT with surgical microscopy makes it possible to evaluate soft tissue in real-time and at a high resolution. Herein, we describe an augmented-reality, intraoperative OCT/microscope system with an extended working distance of 280 mm, providing more space for surgical manipulation than conventional techniques. We initially performed ex vivo experiments to evaluate system performance. In addition, we validated the system by performing preliminary clinical assessments of tympanomastoidectomy outcomes in six patients with chronic otitis media. The system evaluated residual inflammation ...

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    11. Non-destructive identification of weld-boundary and porosity formation during laser transmission welding by using optical coherence tomography

      Non-destructive identification of weld-boundary and porosity formation during laser transmission welding by using optical coherence tomography

      Laser transmission welding offers significant benefits over conventional welding techniques enabling single-stage rapid plastic joining. The quality of laser transmission welded products are commonly assessed by measuring the weld penetration depth, hardened weld boundary, and inspecting the formation of porosity. However, existing methods of verification are inevitably accompanied by destruction of the specimen. Thus, non-destructive quality assessment methods for laser transmission welding have gained attention recently. Here, we demonstrated an extended industrial application of 860 nm wavelength based spectral domain optical coherence tomography for the non-destructive inspection of the aforementioned quality parameters of laser transmission welded industrial plastic materials, i ...

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    12. Assessment of cortical bone microdamage following insertion of microimplants using optical coherence tomography: a preliminary study

      Assessment of cortical bone microdamage following insertion of microimplants using optical coherence tomography: a preliminary study

      Objectives: The study was done to evaluate the efficacy of optical coherence tomography (OCT), to detect and analyze the microdamage occurring around the microimplant immediately following its placement, and to compare the findings with micro-computed tomography (μCT) images of the samples to validate the result of the present study. Methods: microimplant s were inserted into bovine bone samples. Images of the samples were obtained using OCT and μCT. Visual comparisons of the images were made to evaluate whether anatomical details and microdamage induced by microimplant insertion were accurately revealed by OCT. Results: The surface of the cortical bone with its ...

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    13. Biophotonic approach for the characterization of initial bitter-rot progression on apple specimens using optical coherence tomography assessments

      Biophotonic approach for the characterization of initial bitter-rot progression on apple specimens using optical coherence tomography assessments

      The tremendous advances achieved in the biophotonics technologies have intensified the necessity for non-invasive modalities that can characterize diverse biological materials with increased sensitivity and resolution. Optical coherence tomography (OCT) is one of the techniques that has been applied for biological applications in medicine and agriculture to identify structural properties. Herein, we report the successful incorporation of OCT for the identification of morphological changes that occur as a result of the bitter rot disease, through continuous detection of structural changes. Detailed inner morphological structural changes occurring in fruit specimens were precisely analyzed as a function of the disease incubation period ...

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    14. Numerical-Sampling-Functionalized Real-Time Index Regulation for Direct k-Domain Calibration in Spectral Domain Optical Coherence Tomography

      Numerical-Sampling-Functionalized Real-Time Index Regulation for Direct k-Domain Calibration in Spectral Domain Optical Coherence Tomography

      An index-regulation technique functionalized by numerical sampling for direct calibration of the non-linear wavenumber ( k )-domain to a linear domain in spectral domain optical coherence tomography (SD-OCT) is proposed. The objective of the developed method is to facilitate high-resolution identification of microstructures in biomedical imaging. Subjective optical alignments caused by nonlinear sampling of interferograms in the k -domain tend to hinder depth-dependent signal-to-noise ratios (SNR) and axial resolution in SD-OCT. Moreover, the optical-laser-dependent k -domain requires constant recalibrated in accordance with each laser transition, thereby necessitating either hardware or heavy software compensations. As the key feature of the proposed method ...

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    15. Non-Destructive Classification of Diversely Stained Capsicum annuum Seed Specimens of Different Cultivars Using Near-Infrared Imaging Based Optical Intensity Detection

      Non-Destructive Classification of Diversely Stained Capsicum annuum Seed Specimens of Different Cultivars Using Near-Infrared Imaging Based Optical Intensity Detection

      The non-destructive classification of plant materials using optical inspection techniques has been gaining much recent attention in the field of agriculture research. Among them, a near-infrared (NIR) imaging method called optical coherence tomography (OCT) has become a well-known agricultural inspection tool since the last decade. Here we investigated the non-destructive identification capability of OCT to classify diversely stained (with various staining agents) Capsicum annuum seed specimens of different cultivars. A swept source (SS-OCT) system with a spectral band of 1310 nm was used to image unstained control C. annuum seeds along with diversely stained Capsicum seeds, belonging to different cultivar ...

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    16. In Vivo Vibration Measurement of Middle Ear Structure Using Doppler Optical Coherence Tomography: Preliminary Study

      In Vivo Vibration Measurement of Middle Ear Structure Using Doppler Optical Coherence Tomography: Preliminary Study

      Objectives Doppler optical coherence tomography (DOCT) is useful for both, the spatially resolved measurement of the tympanic membrane (TM) oscillation and high-resolution imaging. We demonstrated a new technique capable of providing real-time two-dimensional Doppler OCT image of rapidly oscillatory latex mini-drum and in vivo rat TM and ossicles. Methods Using DOCT system, the oscillation of sample was measured at frequency range of 1–4 kHz at an output of 15 W. After the sensitivity of the DOCT system was verified using a latex mini-drum consisting of a 100 μm-thick latex membrane, changes in displacement of the umbo and contacted area ...

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    17. Multiple Wavelength Optical Coherence Tomography Assessments for Enhanced Ex Vivo Intra-Cochlear Microstructural Visualization

      Multiple Wavelength Optical Coherence Tomography Assessments for Enhanced Ex Vivo Intra-Cochlear Microstructural Visualization

      The precise identification of intra-cochlear microstructures is an essential otorhinolaryngological requirement to diagnose the progression of cochlea related diseases. Thus, we demonstrated an experimental procedure to investigate the most optimal wavelength range, which can enhance the visualization of ex vivo intra-cochlear microstructures using multiple wavelengths (i.e., 860 nm, 1060 nm, and 1300 nm) based optical coherence tomography (OCT) systems. The high-resolution tomograms, volumetric, and quantitative evaluations obtained from Basilar membrane, organ of Corti, and scala vestibule regions revealed complementary comparisons between the aforementioned three distinct wavelengths based OCT systems. Compared to 860 nm and 1300 nm wavelengths, 1060 nm ...

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    18. Quality assessment of the optical thin films using line field spectral domain optical coherence tomography

      Quality assessment of the optical thin films using line field spectral domain optical coherence tomography

      Cross-sectional and three-dimensional images show the effectiveness of the system. In this study, the industrial inspection of optical thin film on touch screen panels was demonstrated using line field spectral domain optical coherence tomography. The conventional Fourier domain optical coherence tomography system requires a single scanner for two-dimensional cross-sectional images and two scanners for volumetric images. Our developed line field spectral domain optical coherence tomography has the advantage of needing only a single scanner for volumetric images, while two-dimensional cross-sectional images are obtained by the parallel acquisition of an illuminated line on a sample using an area camera. Further, the ...

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    19. In Vivo Fascicle Bifurcation Imaging of Rat Sciatic Nerve Using Swept-Source Optical Coherence Tomography

      In Vivo Fascicle Bifurcation Imaging of Rat Sciatic Nerve Using Swept-Source Optical Coherence Tomography

      The sciatic nerve is the longest and widest single nerve in the human body and is responsible for the signal transduction of the entire hind limb region. Its wide nerve dynamic range and size makes it sensitive to injury. The branching and location of the sciatic nerve are important, and unlike histology, optical coherence tomography (OCT) can provide rapid non-destructive cross-sectional images. The sciatic nerves of ten rats were analyzed using swept-source (SS)-OCT. The sufficient depth penetration of the SS-OCT system allowed clear identification of the internal bifurcation point of the external branching and the internal route for the ...

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    20. Defect inspection of actuator lenses using swept-source optical coherence tomography

      Defect inspection of actuator lenses using swept-source optical coherence tomography

      Actuator lens industries have gained an enormous interest with the enhancement of various latest communication devices, such as mobile phone and notebooks. The quality of the aforementioned devices can be degraded due to the internal defects of actuator lenses. Therefore, in this study, we implemented swept-source optical coherence tomography (SS-OCT) system to inspect defects of actuator lenses. Owing to the high-resolution of the SS-OCT system, defected foreign substances between the actuator lenses, defective regions of lenses and surface stains were more clearly distinguished through three-dimensional (3D) and two-dimensional (2D) cross-sectional OCT images. Therefore, the implemented SS-OCT system can be considered ...

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    21. In Vivo Non-Destructive Monitoring of Capsicum Annuum Seed Growth with Diverse NaCl Concentrations Using Optical Detection Technique

      In Vivo Non-Destructive Monitoring of Capsicum Annuum Seed Growth with Diverse NaCl Concentrations Using Optical Detection Technique

      We demonstrate that optical coherence tomography (OCT) is a plausible optical tool for in vivo detection of plant seeds and its morphological changes during growth. To investigate the direct impact of salt stress on seed germination, the experiment was conducted using Capsicum annuum seeds that were treated with different molar concentrations of NaCl. To determine the optimal concentration for the seed growth, the seeds were monitored for nine consecutive days. In vivo two-dimensional OCT images of the treated seeds were obtained and compared with the images of seeds that were grown using sterile distilled water. The obtained results confirm the ...

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    22. The Validity of the Diagnosis of Plant Leaf Infections Using Non-Destructive Optical Inspection Technique and Depth-Scan Signal Analysis

      The Validity of the Diagnosis of Plant Leaf Infections Using Non-Destructive Optical Inspection Technique and Depth-Scan Signal Analysis

      The applicability of non-destructive optical imaging technique for the diagnosis of infected leaf materials was investigated along with a depth-scan (amplitude depth profile) signal analysis. The experimented plant leaf specimens were collected from persimmon plantations and the specimens were categorized into three groups: healthy leaf specimens, infected leaf specimens, and apparently healthy leaf specimens collected from infected trees. The non-destructive diagnosis was performed using 840 nm spectral domain optical coherence tomography (SD-OCT) system. The obtained OCT results confirmed that the proposed method is capable of identifying morphological differences between healthy specimens from infected specimens and partially infected specimens. Therefore, this ...

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    23. Feature Of The Week 09/17/2017: Non-Destructive Analysis of the Internal Anatomical Structures of Mosquito Specimens Using Optical Coherence Tomography

      Feature Of The Week 09/17/2017: Non-Destructive Analysis of the Internal Anatomical Structures of Mosquito Specimens Using Optical Coherence Tomography

      The study of mosquitoes and analysis of their behavior are of crucial importance in the on-going efforts to control the alarming increase in mosquito-borne diseases. Furthermore, a non-destructive and real-time imaging technique to study the anatomical features of mosquito specimens can greatly aid the study of mosquitoes. In this study, we demonstrate the three-dimensional imaging capabilities of optical coherence tomography (OCT) for structural analysis of Anopheles sinensis mosquitoes. The anatomical features of An. sinensis head, thorax, and abdominal regions, along with the morphology of internal structures, such as foregut, midgut, and hindgut, were studied using OCT imaging. Two-dimensional and three-dimensional ...

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    24. Non-Destructive Analysis of the Internal Anatomical Structures of Mosquito Specimens Using Optical Coherence Tomography

      Non-Destructive Analysis of the Internal Anatomical Structures of Mosquito Specimens Using Optical Coherence Tomography

      The study of mosquitoes and analysis of their behavior are of crucial importance in the on-going efforts to control the alarming increase in mosquito-borne diseases. Furthermore, a non-destructive and real-time imaging technique to study the anatomical features of mosquito specimens can greatly aid the study of mosquitoes. In this study, we demonstrate the three-dimensional imaging capabilities of optical coherence tomography (OCT) for structural analysis of Anopheles sinensis mosquitoes. The anatomical features of An. sinensis head, thorax, and abdominal regions, along with the morphology of internal structures, such as foregut, midgut, and hindgut, were studied using OCT imaging. Two-dimensional and three-dimensional ...

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