• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.564-567
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• 2012

Optical fibers are going to be used for telecommunication, image fibers, sensors under irradiation in nuclear power plants and various irradiation facilities. Especially, Temperature detection sensors using Raman light scattering, temperature or strain sensors using fiber gratings, magnet-optical sensors using photo-magnetic effect, are already commercialized. However, When fibers are exposed to ionizing radiation, color centers are formed in fibers which reduces their light transmission, and it is limited in applying under radiation environments. In this study, $Co^{60}$ gamma-ray induced optical attenuation on Ge-doped single mode(SM) fiber has been measured. Gamma-ray is irradiated for 4hours at the dose rate of 0.5kGy/hr, 2kGy/hr, 8kGy/hr. Consequently, gamma-ray induced loss based on radiation effects in Ge-doped SM fiber occur precisely. Furthermore, dose rate effect that the higher dose rate in the same total dose, the more increase loss of optical fiber and annealing effect that the higher the loss after irradiation, the more increase the recovery rate of the loss are observed in the fiber. This results plan to make use of bases in the study of the radiation-hardened optical fiber.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.1
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• pp.25-32
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• 2008

[ $^{169}Yb$ ] industrial NDT sealed sources were developed by using $Yb_2O_3$ pellets as the target and demonstrated for their performance. To produce the pellets, optimal compacting and sintering conditions were determined experimentally. Source holders for $^{169}Yb$ were designed and fabricated. After assembling an active source produced from HANARO with the developed source holder, a demonstration experiment was performed to compare the quality of the radiographs from $^{192}Ir$ and soft X-rays. This demonstration study showed that the developed $^{169}Yb$ produced better radiographs than $^{192}Ir$ for a carbon steel with less than a 4 mm thickness.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.10
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• pp.1298-1304
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• 2019

Since the 9·11 terror attack in 2001, the Maritime Logistics Security System has been strengthened and required X-ray image for every imported cargos from manufacturing countries to United States. For scanning cargos, the container inspection systems use high energy X-rays for examination of contents of a container to check the nuclear, explosive, dangerous and illegal materials. Nowadays, the X-ray cargo scanners are established and used by global technologies for inspection of suspected cargos in the customs agency but these technologies have not been localized and developed sufficiently. In this paper, we propose the X-ray array detector system which is a core component of the container scanning system. For implementation of X-ray array detector, the analog and digital signal processing units are fabricated with integrated hardware, FPGA logics and GUI software for real-time X-ray images. The implemented system is superior in terms of resolution and power consumption compared to the existing products currently used in ports.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.1
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• pp.31-37
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• 2007

A $^{192}Ir$ small-focal source has been developed by using the HANARO reactor and the radioisotope production facility at the Korea Atomic Energy Research Institute (KAERI). The small-focal source with the dimension of 0.5 mm in diameter and 0.5 mm in length was fabricated as an aluminum-encapsulated form by a specially designed pressing equipment. For the estimation of the radioactivity, neutron self-shielding and ${\gamma}-ray$ self-absorption effects on the measured activity was considered. From this estimation, it is realized that $^{192}Ir$ small-focal sources over 3 Ci activities can be produced from the HANARO. Field performance tests were performed by using a conventional source and the developed source to take images of a computer CPU and a piece of a carbon steel. The small-focal source showed better penetration sensitivity and geometrical sharpness than the conventional source does. It is concluded from the tests that the focal dimension of this source is small enough to maximize geometrical sharpness in the image taking for the close proximity shots, pipeline crawler applications and contact radiography.

• Journal of the Korea Concrete Institute
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• v.26 no.4
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• pp.517-524
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• 2014

Nitrite-Type hydrocalumite (calumite) is a material that can adsorb chloride ions ($Cl^-$) that cause corrosion of reinforce bars and liberate the nitrite ions ($NO_2{^-}$) that inhibit corrosion in reinforced concrete. In this study, polymer-modified mortars using two types of epoxy resin with calumite are prepared with various polymer binder-ratios of 0, 5, 10, 15, 20% and calumite contents of 0, 5%. The specimens are tested for chloride ion penetration, carbonation, drying shrinkage and corrosion inhibition. As a result, the chloride ion penetration and carbonation depth of PMM using epoxy resin somewhat increases with increasing calumite contents, but those remarkably decreases depending on the polymer-binder ratios. The 28-d drying shrinkage shows a tendency to decrease with increasing polymer-binder ratio and calumite content. Unmodified mortars with calumite content of 5% did not satisfy quality requirement by KS. However, it was satisfied with KS requirement by the modification of epoxy resin in cement mortar. On the whole, the carbonation and chloride ion penetration depth of epoxy-modified mortars with calumite is considerably improved with an increase in the polymer-binder ratio regardless of the calumite content, and is remarkably improved over unmodified mortar. And, the replacement of the portland cement with the calumite has a marked effect in the corrosion-inhibiting property of the epoxy-modified mortars.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.3
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• pp.275-281
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• 2004

Socket weldment used to change the flow direction of fluid nay have flaws such as lack of fusion and cracks. Liquid penetrant testing or Radiography testing have been applied as NDT methods for flaw detection of the socket weldment. But it is difficult to detect the flaw inside of the socket weldment with these methods. In order to inspect the flaws inside the socket weldment, a ultrasonic testing method is established and a ultrasonic transducer and automated ultrasonic testing system are developed for the inspection. The automated ultrasonic testing system is based on the portable personal computer and operated by the program based Windows 98 or 2000. The system has a pulser/receiver, 100MHz high speed A/D board, and basic functions of ultrasonic flaw detector using the program. For the automated testing, motion controller board of ISA interface type is developed to control the 4-axis scanner and a real time iC-scan image of the automated testing is displayed on the monitor. A flaws with the size of less than 1mm in depth are evaluated smaller than its actual site in the testing, but the flaws larger than 1mm appear larger than its actual size on the contrary. This tendency is shown to be increasing as the flaw size increases. h reliable and objective testing results are obtained with the developed system, so that it is expected that it can contribute to safety management and detection of repair position of pipe lines of nuclear power plants and chemical plants.

• Journal of Radiation Protection and Research
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• v.40 no.1
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• pp.1-9
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• 2015

Compton cameras overcome several limitations of conventional mechanical collimation based gamma imaging devices, such as pin-hole imaging devices, due to its electronic collimation based on coincidence logic. Especially large-scale Compton camera has wide field of view and high imaging sensitivity. Those merits suggest that a large-scale Compton camera might be applicable to monitoring nuclear materials in large facilities without necessity of portability. To that end, our research group have made an effort to design a large-scale Compton camera for safeguard application. Energy resolution or position resolution of large-area detectors vary with configuration style of the detectors. Those performances directly affect the image quality of the large-scale Compton camera. In the present study, a series of Geant4 Monte Carlo simulations were performed in order to examine the effect of those detector parameters. Performance of the designed large-scale Compton camera was also estimated for various monitoring condition with realistic modeling. The conclusion of the present study indicates that the energy resolution of the component detector is the limiting factor of imaging resolution rather than the position resolution. Also, the designed large-scale Compton camera provides the 16.3 cm image resolution in full width at half maximum (angular resolution: $9.26^{\circ}$) for the depleted uranium source considered in this study located at the 1 m from the system when the component detectors have 10% energy resolution and 7 mm position resolution.

• Journal of Animal Environmental Science
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• v.11 no.3
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• pp.153-160
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• 2005

This study was conducted to determine the effect of floor type of finishing building and increasing market weight of finishing Pigs on Performance, carcass traits and pork quality. Four hundred and forty-four finishing pigs were confined and administered with different floor type(concrete slat and bedded with sawdust) and increasing market weight(110kg to 130kg) of finishing building. The result obtained from this study were summarized as follows; 1. There was no significant difference between the floor type of finishing building in the body weight gain, feed intake and gain per feed. And also increasing market weight of finishing pigs was not affected the performance of finishing pigs. 2. Increasing market weight of finishing pigs affect the carcass yield. The market weight at 130kg showed more amount of each cut of carcass, especially the belly portion was higher, but backfat thickness was not different. 3. Carcass traits did not show any significant difference due to the difference of market weight of finishing pig and floor type of finishing building. 4. There was no significant difference in the chemical compositions and meat color of pork loin between the floor type of finishing building and increasing market weight of finishing pigs.