• Journal of Microbiology and Biotechnology
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• v.33 no.1
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• pp.51-60
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• 2023

The foodborne illness is the important public health concerns, and the livestock feces are known to be one of the major reservoirs of foodborne pathogens. Also, it was reported that 45.5% of foodborne illness outbreaks have been associated with the animal products contaminated with the livestock feces. In addition, it has been known that the persistence of a pathogens depends on many potential virulent factors including the various virulent genes. Therefore, the first step to understanding the public health risk of livestock feces is to identify and describe microbial communities and potential virulent genes that contribute to bacterial pathogenicity. We used the whole metagenome shotgun sequencing to evaluate the prevalence of foodborne pathogens and to characterize the virulence associated genes in pig and chicken feces. Our data showed that the relative abundance of potential foodborne pathogens, such as Bacillus cereus was higher in chickens than pigs at the species level while the relative abundance of foodborne pathogens including Campylobacter coli was only detected in pigs. Also, the microbial functional characteristics of livestock feces revealed that the gene families related to "Biofilm formation and quorum sensing" were highly enriched in pigs than chicken. Moreover, the variety of gene families associated with "Resistance to antibiotics and toxic compounds" were detected in both animals. These results will help us to prepare the scientific action plans to improve awareness and understanding of the public health risks of livestock feces.

• Journal of Space Technology and Applications
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• v.3 no.1
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• pp.26-43
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• 2023

As Korean first lunar probe, Danuri, succeeded in entering lunar orbit, Korean new space exploration plans such as Mars exploration can be expected. Korean space exploration payload is developed only in a limited field, so there is a need to create a new space exploration payload. In foreign countries, there is a mass spectrometer as a basic equipment for space exploration, and it is a very useful payload that encompasses the exploration of life through the analysis of organic matter as well as the observation of the atmosphere and volatile substances of the exploration target. However, Korea has never developed a mass spectrometer payload for space exploration, so it is necessary to secure technology in preparation for future space exploration. Before that, we look at the scientific achievements of foreign mass spectrometer payloads for space exploration and identify trends.

• Journal of Space Technology and Applications
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• v.3 no.1
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• pp.86-99
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• 2023

The mass spectrometer, being an essential scientific instrument for uncovering the origin of the solar system and life, has been used since the early 1970s on board spacecraft to obtain information of neutral and ionized elements in the atmosphere and surface of the moon, planets, asteroids, and comets. According to the 4th Basic Plan for the Promotion of Space Development (2023-2027), Korea plans to conduct lunar landing in 2032 and Mars landing in 2045 as the core goals of the plan and focuses on developing the technologies required for unmanned robotic exploration missions. In this regard, it is crucial to develop the technology of a mass spectrometer, which is the most fundamental payload for space exploration for maximized scientific achievements, however never tried before in any domestic space missions. We describe in this paper the principle of a domestically developed quadrupole mass spectrometer, its prototype model, and the test results of its performance. We conclude this paper with intended future improvements.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.175-186
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• 2023

The buffer materials in disposal hole are exposed to the decay heat from spent nuclear fuels and groundwater inflow through adjacent rockmass. Since understanding of thermal-hydro-mechanical-chemical (T-H-M-C) interaction in buffer material is crucial for predicting their long-term performance and safety of disposal repository, it is necessary to investigate the heating-hydration characteristics and consequent T-H-M-C behavior of the buffer materials under disposal conditions considering geochemical factors. In response, the Korea Atomic Energy Research Institute developed a laboratory-scale 'Lab.THMC' experiment system, which characterizes the T-H-M behavior of buffer materials under different geochemical conditions by analyzing heating-hydration process and stress changes. This technical report introduces the detail design of the Lab.THMC system, summarizes preliminary experimental results, and outlines future research plans.

• The Korea Journal of Herbology
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• v.24 no.1
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• pp.111-119
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• 2009

Objectives : To compare the contents of hazardous substances before/after a decoction. Methods : The heavy metal contents before/after a decoction were measured by Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) and mercury analyzer. In order to analyze pesticides in 6 samples we used simultaneous multi-residue analysis of pesticides by GC/ECD, which was followed by GC/MSD analysis to confirm the identity of the detected pesticide in each sample. In addition, the contents of sulfur dioxide (SO2) were performed by Monier-Williams distillation method. Results : 1. The mean values of heavy metal contents (mg/kg) for the samples were as follows: Samchulkunbi-tang (before decoction - Pb; 1.592, Cd; 0.155, As; 0.055 and Hg; 0.014, after decoction - Pb; 0.036, Cd; 0.002, As; not detected and Hg; 0.001), Yijin-tang (before decoction - Pb; 0.830, Cd; 0.077, As; 0.045 and Hg; 0.015, after decoction - Pb; 0.193, Cd; 0.010, As; not detected and Hg; 0.002), Banhabaikchulcheunma-tang (before decoction - Pb; 0.976, Cd; 0.164, As; 0.167 and Hg; 0.019, after decoction - Pb; 0.031, Cd; 0.003, As; 0.006 and Hg; 0.005), Pyungwi-san (before decoction - Pb; 2.162, Cd; 0.128, As; 0.061 and Hg; 0.018, after decoction - Pb; 0.080, Cd; 0.006, As; not detected and Hg; 0.005), Leejung-tang (before decoction - Pb; 1.480, Cd; 0.294, As; 0.034 and Hg; 0.012, after decoction - Pb; 0.064, Cd; 0.007, As; 0.007 and Hg; 0.002) and Kwibi-tang (before decoction - Pb; 0.907, Cd; 0.193, As; 0.085 and Hg; 0.020, after decoction - Pb; 0.072, Cd; 0.006, As; 0.004 and Hg; 0.002). 2. Contents (mg/kg) of sulfur dioxide ($SO_2$) before a decoction in Banhabaikchulcheunma-tang, Pyungwi-san, Leejung-tang and Kwibi-tang exhibited 3.5, 3.4, 3.8 and 12.4, respectively. However, contents of sulfur dioxide after a decoction in all samples were not detected. 3. Contents (mg/kg) of residual pesticides before/after a decoction in all samples were not detected. Conclusions : These results will be used to establish a criterion of heavy metals, residual pesticides and sulfur dioxide.

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.697-704
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• 2021

It is hard to get Filaments which are materials of the 3D printing Fused Deposition Modeling(FDM) method as radiation shielding in Korea. and also related research is insufficient. This study aims to provide basic data for the development of radiation shields using 3D printing by evaluating the physical properties and radiation shielding capabilities of filaments containing metal particles. after selecting five metal filaments containing metal particle reinforcement materials, the radiation shielding rate was calculated according to the Korean Industrial Standard's protective equipment test method to evaluate physical properties such as tensile strength, density, X-ray Diffraction(XRD), and weight measurement using ASTM's evaluation method. In the tensile strength evaluation, PLA + SS was the highest, ABS + W was the lowest, and ABS + W is 3.13 g/cm³ which value was the highest among the composite filaments in the density evaluation. As a result of the XRD, it may be confirmed that the XRD peak pattern of the particles on the surface of the specimen coincides with the pattern of each particle reinforcing material powder metal, and thus it was confirmed that the printed specimen contained powder metal. The shielding effect for each 3D printed composite filament was found to have a high shielding rate in proportion to the effective atomic number and density in the order of ABS + W, ABS + Bi, PLA+SS, PLA + Cu, and PLA + Al. In this study, it was confirmed that the metal particle composite filament containing metal powder as a reinforcing material has radiation shielding ability, and the possibility of using a radiation shielding filament in the future.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1460-1467
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• 2023

A robust approach was conducted to determining the absolute oral bioavailable (f_ab) fractions of ²³⁸U and ²³²Th in rats exposed to contaminated soil along with their hematotoxicity and nephrotoxicity. The soil sample is the International Atomic Energy Agency-312 (IAEA-312) certified reference material, whereas blood, bones, and kidneys of in vivo female Sprague-Dawley (SD) rats estimate ²³⁸U- and ²³²Th-f_ab fractions post-exposure. We predict the bioavailable concentration (C_ab) and f_ab values of ²³⁸U and ²³²Th after acute soil ingestion. The blood ²³⁸U (0.750%) and ²³²Th (0.028%) reach their maximum f_ab values after 48 h. The ²³⁸U (f_ab: 0.169-0.652%) accumulates mostly in the kidney, whereas the ²³²Th (f_ab: 0.004-0.021%) accumulates primarily in the bone. Additionally, ²³⁸U is more bioavailable than ²³²Th. Post 48 h acute ingestion demonstrates noticeable histopathological and hematological alterations, implying that intake of ²³⁸U in co-contaminated soil can lead to erythrocytes and proximal tubules damage, whereas, ²³²Th intake can harm erythrocytes. Our study provides new directions for future research into the health implications of acute oral exposures to ²³⁸U and ²³²Th in co-contaminated soils. The findings offer significant insight into the utilization of in vivo SD rat testing to estimate ²³⁸U and ²³²Th bioavailability and toxicity in exposure assessment.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.1
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• pp.219-227
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• 2017

Current military command information system uses electronic equipment a lot on which semiconductor chip is attached. It seems its' importance will increase more with latest information communication technology developing. Electronic equipment which uses electricity contains regular tolerance to high output electric signal. And EMC specification is the standardized of this electronic equipment's tolerance. On the other hand, the Institute of Atomic Energy Research has ever declared that high output electromagnetic pulse(EMP) will be broken out within the radius of 170Km when 10kt nuclear explosion occurs at an altitude of 40Km above Seoul. Then, the region suffer from the damage of most electronic equipments. Therefore, the norm to protect the influences in that case is defined by EMP protection specification. Most common electronic equipments meet the EMC norm, but there is no way to check whether they meet the EMP norm or not. That is because it is difficult to check whether they meet EMP protection norm and is on the matter of cost. Except inevitable cases, there is no review of checking whether they meet the norm or not. Considering the above, in this research, we speculate about the measures to improve military EMP protection ability by analyzing the EMC-EMP correlation and checking the EMP protection ability of general electronic equipment through the analysis.

• Tunnel and Underground Space
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• v.33 no.3
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• pp.189-207
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• 2023

In the present study, the thermoshearing experiment on a rough rock fracture were modeled using a three-dimensional grain-based distinct element model (GBDEM). The experiment was conducted by the Korea Institute of Construction Technology to investigate the progressive shear failure of fracture under the influence of thermal stress in a critical stress state. The numerical model employs an assembly of multiple polyhedral grains and their interfaces to represent the rock sample, and calculates the coupled thermo-mechanical behavior of the grains (blocks) and the interfaces (contacts) using 3DEC, a DEM code. The primary focus was on simulating the temperature evolution, generation of thermal stress, and shear and normal displacements of the fracture. Two fracture models, namely the mated fracture model and the unmated fracture model, were constructed based on the degree of surface matedness, and their respective behaviors were compared and analyzed. By leveraging the advantage of the DEM, the contact area between the fracture surfaces was continuously monitored during the simulation, enabling an examination of its influence on shear behavior. The numerical results demonstrated distinct differences depending on the degree of the surface matedness at the initial stage. In the mated fracture model, where the surfaces were in almost full contact, the characteristic stages of peak stress and residual stress commonly observed in shear behavior of natural rock joints were reasonably replicated, despite exhibiting discrepancies with the experimental results. The analysis of contact area variation over time confirmed that our numerical model effectively simulated the abrupt normal dilation and shear slip, stress softening phenomenon, and transition to the residual state that occur during the peak stress stage. The unmated fracture model, which closely resembled the experimental specimen, showed qualitative agreement with the experimental observations, including heat transfer characteristics, the progressive shear failure process induced by heating, and the increase in thermal stress. However, there were some mismatches between the numerical and experimental results regarding the onset of fracture slip and the magnitudes of fracture stress and displacement. This research was conducted as part of DECOVALEX-2023 Task G, and we expect the numerical model to be enhanced through continued collaboration with other research teams and validated in further studies.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.2
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• pp.95-106
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• 2023

Quartz (SiO₂) is among the major rock-forming minerals in the earth's crust. The atomistic structures of SiO₂ may evolve during diverse frictional processes. The reduction of friction of quartz-rock accompanied by its amorphization, hydration, and formation of silica gel provides mineralogical insights into earthquakes and related phenomena. Ball milling, together with rotary shear experiments have been useful to infer the atomic origins of such processes. In this study, optimal experimental conditions for ball milling for amorphization of SiO₂ were determined by taking into account various process variables. The crystallinity of SiO₂ gradually decreased and became amorphous as the ball milling time increased at a high milling speed. The degree of wear of the milling media and its effect on the amorphization of SiO₂ were analyzed using distinct milling materials (zirconia, stainless steel). The amount of ball wear increased with increasing milling time. Furthermore, the worn stainless steel particles from balls tend to interact with amorphized SiO₂ to form Si-O-Cr. These results aid in understanding the process of atomistic structural changes caused by ball milling of divserse materials with relatively high hardness, such as SiO₂, and understanding various geological friction processes.