• Journal of the Korea Institute of Building Construction
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• v.18 no.1
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• pp.33-40
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• 2018

Currently, in South Korea, because of reducing the construction period or treating wasted water, there are some cases of missing wet curing for concrete structure even though for high strength concrete. This air curing conditions is considered to cause increased possibility of compressive strength decrease, and increasing drying or autogenous shrinkages. As a solution of shrinkage of concrete, The authors' research team conducted the research on improving durability of concrete with decreasing autogenous shrinkage by adding the oil or fat to induce the saponification. Therefore, in this research, the influence of curing method on compressive strength, shrinkage on evaporation rate of high strength mortar including high volume supplementary cementitious materials (SCMs) was evaluated depending on various curing methods such as air curing, drying after painting emulsified refined cooking oil (ERCO), and drying after 7 and 28 days' wet curing. The experimental result showed the air curing method caused approximately 50% of decreased compressive strength and 1.9 times of increased shrinkage rather than the 28-day-wet curing method, thus it was known that the wet curing significantly influences on performance of high strength mortar using high volume SCMs. However, the ERCO painting curing caused decreased performance of concrete rather than drying after 7 days curing while it caused improved performance of concrete than entire period air curing.

• Current Research on Agriculture and Life Sciences
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• v.2
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• pp.91-97
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• 1984

This study was performed to suggest the basic information for the development of covering method for increasing the effect of heat conservation in the unheated vinyl houses. Double and single covered vinyl houses were constructed and the inside temperature variation of the double covered vinyl house was compared to the single covered vinyl house. The results obtained for the vinyl houses were summarized as follows ; 1. With the outside temperature of $-1.0^{\circ}C{\sim}7.5^{\circ}C$ and the solar radiation of maximum $1.02MJ/m^2$, the double covered vinyl house was shown $1.2^{\circ}C$ higher than the single covered vinyl house in the daily mean of inside temperature. 2. The inside temperature of the double covered vinyl house was $2.3^{\circ}C$ higher in the daytime and $1.2^{\circ}C$ higher in the nighttime than that of the single covered vinyl house. 3. The inside temperature of the vinyl house were expressed by the formular (1)-(6) with the outside temperature and by the formular (7)-(10) with the solar radiation. 4. In the effect of heat conservation based on the outside temperature, the double covered vinyl house was 1.2 times in the daytime and 1.76 times in the nighttime in comparison with the single covered vinyl house.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.749-754
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• 2021

In order to maximize the matching ratio between the scintillation pixel and the photosensor of the PET detector using a small number of photosensor, various arrays of scintillation pixels and four photosensors were used. The array of scintillation pixels consisted of six cases from 6 × 6 to 11 × 11. The distance between the photosensors was applied equally to all scintillation pixels, and the arrangement was expanded by reducing the size of scintillation pixel. DETECT2000 capable of light simulation was used to acquire flood images of the designed PET detectors. At the center of each scintillation pixel array, light generated through the interaction between extinction radiation and scintillation pixels was generated, and the light was detected through for four photosensors, and then a flood image was reconstructed. Through the reconstructed flood image, we found the largest arrangement in which all the scintillation pixels can be distinguished. As a result, it was possible to distinguish all the scintillation pixels in the flood image of 8 × 8 scintillation pixel array, and from the 9 × 9 scintillation pixel flood image, the two edge scintillation pixels overlapped and appeared in the image. At this time, the matching ratio between the scintillation pixel and the photosensor was 16:1. When a PET system is constructed using this detector, the number of photosensors used is reduced and the cost of the oveall system is expected to be reduced through the simplification of the signal processing circuit.

• Journal of the Korean Society of Radiology
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• v.13 no.4
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• pp.661-666
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• 2019

Diverging collimators is used to obtain reduced images of an object, or to detect a wide filed-of-view (FOV) using a small gamma camera. In the gamma camera using the diverging collimators, the block scintillator, and the pixel scintillator array, gamma rays are obliquely incident on the scintillator surface when the source is located the periphery of the FOV. Therefore, the spatial resolution is reduced because it is obliquely detected in depth direction. In this study, we designed a novel system to improve the spatial resolution in the periphery of the FOV. Using a tapered crystal array to configure the scintillation pixels to coincide with the angle of the collimator's hole allows imaging to one scintillation pixel location, even if events occur to different depths. That is, even if is detected at various points in the diagonal direction, the gamma rays interact with one crystal pixel, so resolution does not degrade. The resolution of the block scintillator and the tapered crystal array was compared and evaluated through Geant4 Application for Tomographic Emission (GATE) simulation. The spatial resolution of the obtained image was 4.05 mm in the block scintillator and 2.97 mm in the tapered crystal array. There was a 26.67% spatial resolution improvement in the tapered crystal array compared to the block scintillation.

• Journal of the Korean Society of Radiology
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• v.15 no.1
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• pp.1-7
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• 2021

In order to acquire an image in a positron emission tomography, it is necessary to draw the position coordinates of the scintillation pixels of the detector module measured at the same time. To this end, in a detector module using a plurality of scintillation pixels and a small number of photosensors, it is necessary to obtain a flood image and divide a region of each scintillation pixel to obtain a position of a scintillation pixel interacting with a gamma ray. Alternatively, when the number of scintillation pixels and the number of photosensors to be used are the same, the position coordinates for the position of the scintillation pixels can be directly acquired as digital signal coordinates. A method of using a plurality of scintillation pixels and a small number of photosensors requires a process of obtaining digital signal coordinates requires a plurality of photosensors and a signal processing system. This complicates the signal processing process and raises the cost. To solve this problem, in this study, we developed a method of obtaining digital signal coordinates without performing the process of separating the planar image and region using a plurality of flash pixels and a small number of optical sensors. This is a method of obtaining the position coordinate values of the flash pixels interacting with the gamma ray as a digital signal through a look-up table created through the signals acquired from each flash pixel using the maximum likelihood function. Simulation was performed using DETECT2000, and verification was performed on the proposed method. As a result, accurate digital signal coordinates could be obtained from all the flash pixels, and if this is applied to the existing system, it is considered that faster image acquisition is possible by simplifying the signal processing process.

• Journal of the Korean Society of Radiology
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• v.17 no.1
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• pp.25-30
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• 2023

As 3D printing technology is used in the medical field, interest in metal materials is increasing. The Department of Radiation Oncology uses a shielding block to shield the patient's normal tissue from unnecessary exposure during electron beam therapy. However, problems such as handling of heavy metal materials such as lead and cadmium, reproducibility according to skill level and uncertainty of arrangement have been reported. In this study, candidate materials that can be used for metal 3D printing are selected, and the physical properties and radiation dose of each material are analyzed to develop a customized shielding block that can be used in electron beam therapy. As candidate materials, aluminum alloy (d = 2.68 g/cm³), titanium alloy (d = 4.42 g/cm³), and cobalt chromium alloy (d = 8.3 g/cm³) were selected. The thickness of the 95% shielding rate point was derived using the Monte Carlo Simulation with the irradiation surface and 6, 9, 12, and 16 energies. As a result of the simulation, among the metal 3D printing materials, cobalt chromium alloy (d = 8.3 g/cm³) was similar to the existing shielding block (d = 9.4 g/cm³) in shielding thickness for each energy. In a follow-on study, it is necessary to evaluate the usefulness in clinical practice using customized shielding blocks made by metal 3D printing and to verify experiments through various radiation treatment plan conditions.

• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.815-824
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• 2022

The current radiation safety management system is also applied to radiation practices at universities. The application of the law raised concerns about poor radiation practice education and hindering the development of radiology. Accordingly, the Korean Radiology Professors Association needed to grasp the reality of the management system for radiation practice education at each university and the current radiation safety management system in the department of Radiological science. So, a survey was conducted on heads of radiological science departments across the country. Through the survey, it was found that the current application of the Nuclear Safety Act to radiation safety management in the department of Radiological science is excessively restrictive and not very effective. In addition, radiology practice education for the purpose of training health and medical professionals should be controlled by the Ministry of Health and Welfare and the Korea Centers for Disease Control, but there is a problem of being supervised by the Nuclear Safety and Security Commission. Therefore, in this study, as a legal improvement plan to solve this problem, first, a plan according to a partial amendment to the Higher Education Act, second, a plan to be supervised by the Ministry of Health and Welfare through the amendment of article 37 of the Medical Service Act, third, article 20-2 of the Enforcement Decree of the Medical Service Technologists Act was newly inserted to propose three measures to be supervised by the Ministry of Health and Welfare.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.133-137
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• 2017

The purpose of this study was to validate for GATE (Geant4 Application for Tomographic Emission) simulation by comparing the results of GATE simulation and experiment in real SPECT system. Futhermore, we want to prove that it is possible that the quantitative research of gamma camera/SPECT imaging for therapeutic radio isotope by using GATE simulation. In this study, the SPECT system on simulation referred to the parameters of Stream-R Forte version 1.2 (Philips Medical System, Best and Heerlen, Netherlands). To understand the I-131 image of gamma camera/SPECT system, we acquired the energy spectrum and measured the full width at half maximum (FWHM) which comes from line spread function (LSF) with and without scatter material in real SPECT system. And to compare with experiment, we also measured the FWHM and acquired the energy spectrum without scatter material in GATE simulation. As a result, without scatter material, the energy peak was almost same location, which are located nearby 364 keV, and other spectrum factors are same tendency in both cases. The FWHM was increased by increasing the distance of source to detector, and the error rate was approximately 3.8%. When we used the line source with scatter material, energy spectrum also indicated similar tendency in both cases. As you confirmed earlier, GATE simulation included real instrument and radioisotope characters for therapeutic radioisotope. Therefore this result that it was possible that various quantitative study for therapeutic radioisotope imaging in gamma camera/SPECT using GATE simulation.

• Journal of Radiation Protection and Research
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• v.39 no.4
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• pp.199-205
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• 2014

In the field of neutron detections, $^3He$ gas, the so-called "the gold standard," is the most widely used material for neutron detections because of its high efficiency in neutron capturing. However, from variable causes since early 2009, $^3He$ is being depleted, which has maintained an upward pressure on its cost. For this reason, the demands for $^3He$ replacements are rising sharply. Research into neutron converting materials, which has not been used well due to a neutron detection efficiency lower than the efficiency of $^3He$, although it can be chosen for use in a neutron detector, has been highlighted again. $^{10}B$, which is one of the $^3He$ replacements, such as $BF_3$, $^6Li$, $^{10}B$, $Gd_2O_2S$, is being researched by various detector development groups owing to a number of advantages such as easy gamma-ray discrimination, non-toxicity, low cost, etc. One of the possible techniques for the detection is an indirect neutron detection method measuring secondary radiation generated by interactions between neutrons and $^{10}B$. Because of the mean free path of alpha particle from interactions that are very short in a solid material, the thickness of $^{10}B$ should be thin. Therefore, to increase the neutron detection efficiency, it is important to make a $^{10}B$ thin film. In this study, we fabricated a $^{10}B$ thin film that is about 60 um in thickness for neutron detection using well-known technology for the manufacturing of a thin electrode for use in lithium ion batteries. In addition, by performing simple physical tests on the conductivity, dispersion, adhesion, and flexibility, we confirmed that the physical characteristics of the fabricated $^{10}B$ thin film are good. Using the fabricated $^{10}B$ thin film, we made a proportional counter for neutron monitoring and measured the neutron pulse height spectrum at a neutron facility at KAERI. Furthermore, we calculated using the Monte Carlo simulation the change of neutron detection efficiency according to the number of thin film layers. In conclusion, we suggest a fabrication method of a $^{10}B$ thin film using the technology used in making a thin electrode of lithium ion batteries and made the $^{10}B$ thin film for neutron detection using suggested method.

• Cross-Cultural Studies
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• v.51
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• pp.291-327
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• 2018

'Hyesung' and 'Jeilsun' are media that reveal the new searches of the Gaebyeoksa Publishing Company of the 1930s. However, studies in the past did not sufficiently analyze their significance. Furthermore, there are no analyses on how the critical minds of 'Hyesung' and 'Jeilsun' were linked to 'Gaebyeok', which continued publications in 1934. The 1930s when 'Hyesung' and 'Jeilsun' were published, was a time where the media of colonial Chosun was rapidly changing, and it was a time where literary magazines were increasing in quantity. In the 1930s, Gaebyeoksa attempted to actively respond to such changes reflected in the media. This was demonstrated through the publication of the new media 'Hyesung' and 'Jeilsun' and continuing publication of the 'Gaebyeok' magazine in 1935. This study analyzed the literary discourses shown in the magazines published by Gaebyeoksa in the 1930s based on 'Hyesung', 'Jeilsun', and the continued publication of 'Gaebyeok'. Through such analysis, this study examined how the magazines published by Gaebyeoksa perceived the culture and literature of colonial Chosun in the 1930s and in which direction it tried to reorganize this.