• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.1
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• pp.17-27
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• 2019

In this paper, we study the applicability of Tuned Mass Damper(TMD) to improve seismic performance of piping system under earthquake loading. For this purpose, a mode analysis of the target pipeline is performed, and TMD installation locations are selected as important modes with relatively large mass participation ratio in each direction. In order to design the TMD at selected positions, each corresponding mode is replaced with a SDOF damped model, and accordingly the corresponding pipeline is converted into a 2-DOF system by considering the TMD as a SDOF damped model. Then, optimal design values of the TMD, which can minimize the dynamic amplification factor of the transformed 2-DOF system, are derived through GA optimization method. The proposed TMD design values are applied to the pipeline numerical model to analyze seismic performance with and without TMD installation. As a result of numerical analyses, it is confirmed that the directional acceleration responses, the maximum normal stresses and directional reaction forces of the pipeline system are reduced, quite a lot. The results of this study are expected to be used as basic information with respect to the improvement of the seismic performance of the piping system in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.276-284
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• 2019

Seismic research on bridges, dams and nuclear power plants, which are infrastructure in Korea, has been carried out since early on, but in the case of structures in thermal power plants, research is insufficient. In this study, a total of 192 dynamic analyzes were performed for 16 actual seismic waves and 12 PGAs. As a result, the probability of failure increased as the PGA value increased for each applied seismic wave, but it was different for each seismic wave. As a result, at 0.22G, the ratio of the compressive limit reached to the limit state was 25% and the ratio of the relative displacement reached the limit state was 13%. So, the probability of collapse due to compressive failure Is higher. Therefore, the fragility curve of the chimney which is the subject of this study can be used as a quantitative basis to determine the limit state of the target structure when an earthquake occurs and to be used for the safety design of the thermal power plants.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.4
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• pp.491-505
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• 2018

As an alternative to deep geological disposal technology, which is considered as a reference concept, the domestic applicability of deep borehole disposal technology for high level radioactive waste, including spent fuel, has been preliminarily evaluated. Usually, the environment of deep borehole disposal, at a depth of 3 to 5 km, has more stable geological and geo-hydrological conditions. For this purpose, the characteristics of rock distribution in the domestic area were analyzed and drilling and investigation technologies for deep boreholes with large diameter were evaluated. Based on the results of these analyses, design criteria and requirements for the deep borehole disposal system were reviewed, and preliminary reference concept for a deep borehole disposal system, including disposal container and sealing system meeting the criteria and requirements, was developed. Subsequently, various performance assessments, including thermal stability analysis of the system and simulation of the disposal process, were performed in a 3D graphic disposal environment. With these analysis results, the preliminary evaluation of the domestic applicability of the deep borehole disposal system was performed from various points of view. In summary, due to disposal depth and simplicity, the deep borehole disposal system should bring many safety and economic benefits. However, to reduce uncertainty and to obtain the assent of the regulatory authority, an in-situ demonstration of this technology should be carried out. The current results can be used as input to establish a national high-level radioactive waste management policy. In addition, they may be provided as basic information necessary for stakeholders interested in deep borehole disposal technology.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.3
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• pp.313-319
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• 2019

The A-KRS (Advanced Korean Reference Disposal System) is the disposal concept for pyroprocessed waste, which has been developed by the Korea Atomic Energy Research Institute. In this disposal concept, the amount of high-level radioactive waste is minimized using pyrochemical process, called pyroprocessing. The produced pyroprocessed waste is then solidified in the form of monazite ceramic. The final product of ceramic wastes will be disposed of in a deep geological repository. By the way, the decay heat is generated due to the radioactive decay of fission products and raises the temperature of buffer materials in the near field of radioactive waste repository. However, the buffer temperature must be kept below $100^{\circ}C$ according to the safety regulation. Usually, the temperature can be controlled by variation of the canister interdistance. However, KAERI has modelled thermal analysis under the boundary condition, where the waste canisters are in direct contact with each other. Therefore, a reliable temperature analysis in the disposal system may fail because of unknown thermal resistence values caused by the spatial gap between waste canisters. In the present work, we have performed thermal analyses considering the gap between heating elements and canisters at the beginning of canister loading into the radioactive waste repository. All thermal analyses were performed using the COMSOL software package.

• Korean Journal of Clinical Laboratory Science
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• v.53 no.1
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• pp.1-10
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• 2021

Radiopharmaceuticals are drugs that contain radioisotopes and are used in the diagnosis, treatment, or investigation of diseases. Radiopharmaceuticals must be manufactured in compliance with good manufacturing practice regulations and subjected to quality control before they are administered to patients to ensure the safety of the drug. Radiopharmaceuticals for administration to humans need to be sterile and pyrogen-free. Hence, sterility tests and membrane filter integrity tests are carried out to confirm the asepticity of the finished drug product, and a bacterial endotoxin test conducted to assess contamination, if any, by pyrogens. The physical appearance and the absence of foreign insoluble substances should be confirmed by a visual inspection. The chemical purity, residual solvents, and pH should be evaluated because residual by-products and impurities in the finished product can be harmful to patients. The half-life, radiochemical purity, radionuclidic purity, and strength need to be assessed by analyzing the radiation emitted from radiopharmaceuticals to verify that the radioisotope contents are properly labeled on pharmaceuticals. Radiopharmaceuticals always carry the risk of radiation exposure. Therefore, the time taken for quality control tests should be minimized and care should be taken to prevent radiation exposure during handling. This review discusses the quality control procedures and acceptance criteria for a diagnostic radiopharmaceutical.

• Journal of Life Science
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• v.32 no.7
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• pp.491-500
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• 2022

HK shiitake mushroom mycelium (HKSMM), containing 14% β-glucan, is a health functional food ingredient individually approved by the Korea Ministry of Food and Drug Safety for liver health. The anti-inflammatory effect of a 50% aqueous ethanol extract of HKSMM (designated HKSMM50) was studied in RAW 264.7 macrophage cells treated with lipopolysaccharide (LPS). An active hexose correlated compound (AHCC) was used as a positive control. LPS-activated RAW 264.7 cells were treated with HKSMM50 and AHCC (0, 20, 100, 500 ㎍/ml) and cultured for 24 hr. Inflammation-related elements in the supernatant were measured using enzyme-linked immunosorbent assay (ELISA) kits, and the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins in the cells was analyzed by Western blotting. The HKSMM50 lowered iNOS and COX-2 protein expressions, and nuclear factor-kappa B (NF-κB), nitric oxide (NO) and prostaglandin E₂ (PGE₂) contents in a concentration-dependent manner as compared to LPS treatment. Similarly, the HKSMM50 lowered the content of pro-inflammatory cytokines interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-4 (IL-4) and interleukin-6 (IL-6) contents and increased the activity of antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT). The efficacy of the AHCC treatment was similar to that of the HKSSM50 treatments. These results indicate that HKSMM50 showed an anti-inflammatory effect in LPS-treated RAW 264.7 cells by down-regulation of NF-κB signaling and suggest that HKSMM could be used as a health functional food ingredient to help improve immune function.

• Journal of the Korean Orthopaedic Association
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• v.56 no.4
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• pp.305-309
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• 2021

Purpose: This study analyzed the increase in disposal rate of femoral heads in the bone bank of a single hospital from medical disease and drug history, as assessed by the Korean health insurance review and assessment service. Materials and Methods: The disposal rate and cause of 340 femoral heads were analyzed according to the regulations of the bone bank based on the standard model of the Ministry of food and drug safety. Results: One hundred and seven (33%) of 323 femoral heads collected from 2009 to 2018, and 65 (46%) of 142 femoral heads collected from 2015 to 2018 were discarded. The most common causes were related to the history of dementia and the administration of radioisotope for nuclear medicine. Conclusion: The current methods and screening tools can lead to errors in disposing of the available tissues in a bone bank. Thus, improved standards and screening methods are needed.

• Analytical Science and Technology
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• v.35 no.6
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• pp.256-266
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• 2022

It is important to determine the concentration of long-lived radionuclides (e.g., ¹²⁹I) in nuclear waste to ensure safety when handling it. To analyze nuclides in a solid sample (e.g., concrete and soil), it is essential to effectively separate and purify the nuclides of interest in the sample. This study reports the comprehensive efforts made to validate the analytical procedure for ¹²⁹I detection in solid samples, using a high-temperature combustion furnace. ¹²⁹I volatilized from the sample collected in 0.01 M HNO₃ solution with a reducing agent (e.g., NaHSO₃) and was rapidly measured by ICP-MS. Analytical conditions, such as pyrolysis temperature and types of mobile phase gas, catalyst, and trapping solution, were optimized to obtain a high recovery rate of spiked ¹²⁹I. Finally, the optimized method was applied for the simultaneous analysis of other volatile radionuclides, such as ³H and ¹⁴C. The performance test results for the optimized method confirmed that the LSC (for ³H and ¹⁴C) and ICP-MS (for ¹²⁹I) measurements, with the separation of volatile nuclides using a high-temperature combustion furnace, were reliable.

• Journal of the Korean Geotechnical Society
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• v.39 no.4
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• pp.31-44
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• 2023

A base expansion micropile was developed to improve the bearing capacity of the micropile, which bears a simple device installed at the pile base. Under an axial load, this base expansion structure radially expands at the pile tip and attaches itself around ground, compressing the boring wall in the construction stage. In this study, conventional and base expansion micropiles were constructed in the weathered rock where micropiles are commonly installed. Further, field load tests were conducted to verify the bearing capacity enhancement effect. From the load test results, it was revealed that the shaft resistance of base expansion micropiles was about 12% higher than that of conventional micropiles. The load transfer analysis results also showed that compared to conventional micropiles, the unit skin friction and unit end bearing of base expansion micropiles were 15.4% and 315.1% higher, respectively, in the bearing zone of the micropile.

• Journal of the Korean Geotechnical Society
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• v.38 no.3
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• pp.35-42
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• 2022

The N-value from the Standard Penetration Test (SPT), which is one of the representative in-situ test, is an important index that provides basic geological information and the depth of the bearing layer for the design of geotechnical structures. In the aspect of time and cost-effectiveness, there is a need to carry out a representative sampling test. However, the various variability and uncertainty are existing in the soil layer, so it is difficult to grasp the characteristics of the entire field from the limited test results. Thus the spatial interpolation techniques such as Kriging and IDW (inverse distance weighted) have been used for predicting unknown point from existing data. Recently, in order to increase the accuracy of interpolation results, studies that combine the geotechnics and deep learning method have been conducted. In this study, based on the SPT results of about 22,000 holes of ground survey, a comparative study was conducted to predict the depth of the bearing layer using deep learning methods and IDW. The average error among the prediction results of the bearing layer of each analysis model was 3.01 m for IDW, 3.22 m and 2.46 m for fully connected network and PointNet, respectively. The standard deviation was 3.99 for IDW, 3.95 and 3.54 for fully connected network and PointNet. As a result, the point net deep learing algorithm showed improved results compared to IDW and other deep learning method.