• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.804-806
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• 2004

As a noninvasive imaging meathod, optical coherence tomography system has been extensively studied because it has some advantage such as imaging of high resolution, low cost, and compace size configuration. The optical power of the sample signal reflected from an object is usually very small in optical coherence tomography(OCT) due to absorption and scattering in a sample material. Furthermore, there happens a serious loss of sample signal power in a fiber coupler because it does not transfer to a photodetector but return to the optical source. In order to improve the SNR of OCT system, basic Michelson and Mach-Zehnder interferometer types were configured then, we compared simulation with measurement of reference sample Therefore, an On in configuration of Math-Zehnder interferometer was demonstrated in order to improve the signal to noise ratio

• Nuclear Engineering and Technology
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• v.51 no.5
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• pp.1417-1427
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• 2019

In this study, we evaluated the performance of a commercial pixelated cadmium zinc telluride (CZT) detector for spectroscopy and identified its feasibility as a Compton camera for radiation monitoring in a nuclear power plant. The detection system consisted of a $20mm{\times}20mm{\times}5mm$ CZT crystal with $8{\times}8$ pixelated anodes and a common cathode, in addition to an application specific integrated circuit. The performance of the various radioisotopes $^{57}Co$, $^{133}Ba$, $^{22}Na$, and $^{137}Cs$ was evaluated. In general, the amplitude of the induced signal in a CZT crystal depends on the interaction position and material non-uniformity. To minimize this dependency, a drift time correction was applied. The depth of each interaction was calculated by the drift time and the positional dependency of the signal amplitude was corrected based on the depth information. After the correction, the Compton regions of each spectrum were reduced, and energy resolutions of 122 keV, 356 keV, 511 keV, and 662 keV peaks were improved from 13.59%, 9.56%, 6.08%, and 5%-4.61%, 2.94%, 2.08%, and 2.2%, respectively. For the Compton imaging, simulations and experiments using one $^{137}Cs$ source with various angular positions and two $^{137}Cs$ sources were performed. Individual and multiple sources of $^{133}Ba$, $^{22}Na$, and $^{137}Cs$ were also measured. The images were successfully reconstructed by weighted list-mode maximum likelihood expectation maximization method. The angular resolutions and intrinsic efficiency of the $^{137}Cs$ experiments were approximately $7^{\circ}-9^{\circ}$ and $5{\times}10^{-4}-7{\times}10^{-4}$, respectively. The distortions of the source distribution were proportional to the offset angle.

• Current Optics and Photonics
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• v.3 no.3
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• pp.256-262
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• 2019

Extensive tumor resection accompanied by radiotherapy and chemotherapy is the standard of care for malignant gliomas. However, there is a significant obstacle to the complete resection of the tumor due to the difficulty of distinguishing tumor and normal brain tissue with a conventional surgical microscope. Recently, multiple studies have shown the possibility of fluorescence-guided surgery in malignant gliomas. The most used fluorescence dyes for brain tumor surgery are 5-aminolevulinic acid (5-ALA) and indocyanine green (ICG). In this paper, a new fluorescence guided operation system, which can detect both 5-ALA and ICG fluorescent images simultaneously, is presented. This operation system consists of light emitting diodes (LEDs) which emits 410 nm and 740 nm wavelengths. We have performed experiments on rats in order to verify the operation of the newly developed operation system. Oral administration and imaging were performed to observe the fluorescence of 5-ALA and ICG fluorescence in rats. When LEDs at wavelengths of 410 nm and 740 nm were irradiated on rats, 628 nm wavelength with a violet fluorescence color and 825 nm wavelength with a red fluorescence color were expressed in 5-ALA and ICG fluorescent material, respectively, thus we were able to distinguish the tumor tissues easily. Previously, due to the poor resolution of the conventional surgical microscope and the fact that the color of the vein is similar to that of the tumor, the tumor resection margin was not easy to observe, thus increasing the likelihood for cancer recurrence. However, when the tumor is observed through the fluorescence guided operation system, it is possible to easily distinguish the color with the naked eye and it can be completely removed. Therefore, it is expected that surgical removal of cancerous tumors will be possible and surgical applications and surgical microscopes for cancer tumor removal surgery will be promising in the future.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.6 no.2
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• pp.102-115
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• 2020

In the state of Positronium (Ps), which is an unstable material created by the temporary combination of electrons and positrons, the imaging technology through photo-conversion methodology is emerging as a new research theme under resonance conditions through terahertz electromagnetic waves. Normally, Positronium can be observed in the positron emission computed tomography (PET) process when an unstable, separate state that remains after the pair annihilation of an electron and a positron remains. In this study, terahertz (THz) waves and Cherenkov radiation (CR) are generated using the principle of ponderomotive force in the plasma wake-field acceleration, and electrons and positrons are simultaneously generated by using a relativistic electron beam without using a PET device. We confirm the possibility of Positronium photoconversion technology in terahertz electromagnetic resonance conditions through experimental studies that generate an unstable state. Here, a relativistic electron beam (REB) energy of 0.5 MeV (γ=2) was used, and the terahertz wave frequencies is G-band. Meanwhile, a THz wave mode converting three-stepped axicon lens was used to apply the photoconversion technology. Through this, light emission in the form of a luminescence-converted Bessel beam can be verified. In the future, it can be used complementarily with PET in nuclear medicine in the field of medical imaging.

• Journal of Veterinary Science
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• v.24 no.4
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• pp.46.1-46.12
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• 2023

Background: Heartworm infection in dogs is caused by Dirofilaria immitis and common in shelter animals and outdoors dogs. Caval syndrome can develop with severe infection and physical heartworm removal is essential with heartworm burdens. In this study, we used an improved transvenous heartworm extraction brush, which was expected to cause less cardiovascular damage and allow easier manipulation. Objectives: This study aims to evaluate efficacy of this improved transvenous heartworm extraction brush. Methods: The brush was designed to improve upon the limitations of the previous brush-type devices. The brush was made of a polyvinyl chloride tube and threads of polyamides or polyglyconates. Metal material was inserted at the front tip for easy visualization under fluoroscopy. The eight dogs diagnosed with caval syndrome with large numbers of heartworms and pulmonary hypertension were used in this study. The removal procedure began with the dissection of the subcutaneous tissue around the right jugular vein. The device was inserted through the jugular vein. After insertion, the tube was rotated to catch the heartworms and extracted with the heartworms hanging on the threads. The procedure was repeated several times. Lastly, jugular vein and skin sutures were made. Adulticidal therapy was administered after heartworm removal. Results: The mean number of removed heartworms was 10.5 ± 4.24 and mean number of remaining heartworms was 0.63 ± 1.06. Total procedure time was 72.63 ± 51.36. Except for three cases, heartworms were not detected on ultrasonography after the procedure. No procedure-related side effects were observed within the 1- to 2-mon. Conclusions: An improved transvenous heartworm extraction brush is efficient for heartworm removal in dogs with caval syndrome.

• Food Science of Animal Resources
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• v.43 no.6
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• pp.1150-1169
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• 2023

Edible insects are gaining popularity as a potential future food source because of their high protein content and efficient use of space. Black soldier fly larvae (BSFL) are noteworthy because they can be used as feed for various animals including reptiles, dogs, fish, chickens, and pigs. However, if the edible insect industry is to advance, we should use automation to reduce labor and increase production. Consequently, there is a growing demand for sensing technologies that can automate the evaluation of insect quality. This study used short-wave infrared (SWIR) hyperspectral imaging to predict the proximate composition of dried BSFL, including moisture, crude protein, crude fat, crude fiber, and crude ash content. The larvae were dried at various temperatures and times, and images were captured using an SWIR camera. A partial least-squares regression (PLSR) model was developed to predict the proximate content. The SWIR-based hyperspectral camera accurately predicted the proximate composition of BSFL from the best preprocessing model; moisture, crude protein, crude fat, crude fiber, and crude ash content were predicted with high accuracy, with R² values of 0.89 or more, and root mean square error of prediction values were within 2%. Among preprocessing methods, mean normalization and max normalization methods were effective in proximate prediction models. Therefore, SWIR-based hyperspectral cameras can be used to create automated quality management systems for BSFL.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.2_2
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• pp.437-443
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• 2024

The purpose of radiological Dispersal Device(RDD) is to kill people by explosives and to cause radiation exposure by dispersing radioactive materials. And It is a form of explosive that combines radioactive materials such as Co-60 and Ir-192 with improvised explosives. In this study, we tested and evaluated whether it was possible to read the internal structure of an explosive using X-rays in a radioactive explosive situation. The improvised explosive device was manufactured using 2 lb of model TNT explosives, one practice detonator, one 9V battery, and a timer switch in a leather briefcase measuring 41×35×10 cm³. The radioactive material used was the Co-60 source used in the low-level gamma ray irradiation device operated at the Advanced Radiation Research Institute of the Korea Atomic Energy Research Institute. The radiation dose used was gamma ray energy of 1.17 MeV and 1.33 MeV from a Co-60 source of 2208 Ci. The dose rates are divided into 0.5, 1, 2, and 4 Gy/h, and the exposure time was divided into 1, 3, 5, and 10 minutes. Co-60 source was mixed with the manufactured explosive and X-ray image reading was performed. As a result of the experiment, the X-ray image appeared black in all conditions divided by dose rate and time, and it was impossible to confirm the internal structure of the explosive. This is because γ-rays emitted from radioactive explosives have higher energy and stronger penetrating power than X-rays, so it is believed that imaging using X-rays is limited By blackening the film. The results of this study are expected to be used as basic data for research and development of X-ray imaging that can read the internal structure of explosives in radioactive explosive situations.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.243-249
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• 2019

The purpose of this study is to analyze the reflectance of bed materials according to changes in the water level using a drone-based hyperspectral sensor. For this purpose, we took hyperspectral images of bed materials such as soil, gravel, cobble, reed, and vegetation to compare and analyze the spectral data of each material. To adjust the water level, we constructed an experimental channel to control the discharge and installed the bed materials within the channel. In this study, we configured 3 cases according to the water level (0.0 m, 0.3 m, 0.6 m). After the imaging process, we used the mean value of 10 points for each bed material as analytical data. According to the analysis, each material showed a similar reflectance by wavelength and the intrinsic reflectance characteristics of each material were shown in the visible and near-infrared region. Also, the deeper the water level, the lower the peak reflectance in the visible and near-infrared region, and the rate of decrease differed depending on the bed material. We expect the intrinsic properties of these bed materials to be used as basic research data to evaluate river environments in the future.

• Journal of Korea Water Resources Association
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• v.56 no.4
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• pp.235-243
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• 2023

Due to the revision of the River Act and the enactment of the Act on the Investigation, Planning, and Management of Water Resources, a regular bed change survey has become mandatory and a system is being prepared such that local governments can manage water resources in a planned manner. Since the topography of a bed cannot be measured directly, it is indirectly measured via contact-type depth measurements such as level survey or using an echo sounder, which features a low spatial resolution and does not allow continuous surveying owing to constraints in data acquisition. Therefore, a depth measurement method using remote sensing-LiDAR or hyperspectral imaging-has recently been developed, which allows a wider area survey than the contact-type method as it acquires hyperspectral images from a lightweight hyperspectral sensor mounted on a frequently operating drone and by applying the optimal bandwidth ratio search algorithm to estimate the depth. In the existing hyperspectral remote sensing technique, specific physical quantities are analyzed after matching the hyperspectral image acquired by the drone's path to the image of a surface unit. Previous studies focus primarily on the application of this technology to measure the bathymetry of sandy rivers, whereas bed materials are rarely evaluated. In this study, the existing hyperspectral image-based water depth estimation technique is applied to rivers with vegetation, whereas spatio-temporal hyperspectral imaging and cross-sectional hyperspectral imaging are performed for two cases in the same area before and after vegetation is removed. The result shows that the water depth estimation in the absence of vegetation is more accurate, and in the presence of vegetation, the water depth is estimated by recognizing the height of vegetation as the bottom. In addition, highly accurate water depth estimation is achieved not only in conventional cross-sectional hyperspectral imaging, but also in spatio-temporal hyperspectral imaging. As such, the possibility of monitoring bed fluctuations (water depth fluctuation) using spatio-temporal hyperspectral imaging is confirmed.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.250-254
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• 2002

Intergranular corrosion of austenitic stainless steels is a conventional and momentous problem during welding and high temperature use. One of the major reasons for such intergranular corrosion is so-called sensitization, i.e., chromium depletion due to chromium carbide precipitation at grain boundaries. Conventional methods for preventing sensitization of austenitic stainless steels include reduction of carbon content in the material, stabilization of carbon atoms as non-chromium carbides by the addition of titanium, niobium or zirconium, local solution-heat-treatment by laser beam, etc. These methods, however, are not without drawbacks. Recent grain boundary structure studies have demonstrated that grain boundary phenomena strongly depend on the crystallographic nature and atomic structure of the grain boundary, and that grain boundaries with coincidence site lattices are immune to intergranular corrosion. The concept of "grain boundary design and control", which involves a desirable grain boundary character distribution, has been developed as grain boundary engineering. The feasibility of grain boundary engineering has been demonstrated mainly by thermomechanical treatments. In the present study, a thermomechanical treatment was tried to improve the resistance to the sensitization by grain boundary engineering. A type 304 austenitic stainless steel was pre-strained and heat-treated, and then sensitized, varying the parameters (pre-strain, temperature, time, etc.) during the thermomechanical treatment. The grain boundary character distribution was examined by orientation imaging microscopy. The intergranular corrosion resistance was evaluated by electrochemical potentiokinetic reactivation and ferric sulfate-sulfuric acid tests. The sensitivity to intergranular corrosion was reduced by the thermomechanical treatment and indicated a minimum at a small roll-reduction. The frequency of coincidence-site-lattice boundaries indicated a maximum at a small strain. The ferric sulfate-sulfuric acid test showed much smaller corrosion rate in the thermomechanically-treated specimen than in the base material. An excellent intergranular corrosion resistance was obtained by a small strain annealing at a relatively low temperature for long time. The optimum parameters created a uniform distribution of a high frequency of coincidence site lattice boundaries in the specimen where corrosive random boundaries were isolated. The results suggest that the thermomechanical treatment can introduce low energy segments in the grain boundary network by annealing twins and can arrest the percolation of intergranular corrosion from the surface.