• Journal of the Korea Society for Simulation
• /
• v.30 no.1
• /
• pp.103-112
• /
• 2021

In recent years, public bicycle systems are widely spread over the world according to the development of ICT technology. Since the public bicycle systems in large cities need to secure both publicity and convenience for citizens, analysis of various their issues from introduction to operation is required. In addition, it is also necessary to prepare for various scenarios for coexistence with the PM business, which is recently in the spotlight as a last mile means and normally managed privately. This paper introduces modeling and simulation for efficient operations of public bicycle systems. In particular, the proposed method was developed in a form that can be easily used in other cities by modeling the general structure and behavior of the public bicycle system, and it was developed to facilitate modification and expansion of the future model with a component-based model configuration. This paper provides a case study of the propose method, which is the public bicycle simulation in Sejong City. The simulation results were derived by applying the data from the public bicycle system of Sejong City, and they were verified with the associated real data of Sejong City. Using the verified model, it is expected that it can be used as a tool to design and analyze various services on the public bicycle systems, which were especially suitable for Sejong City.

• Korean Journal of Clinical Laboratory Science
• /
• v.53 no.1
• /
• pp.1-10
• /
• 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 the Korea Convergence Society
• /
• v.13 no.3
• /
• pp.125-131
• /
• 2022

Recently, the prevalence of remotely managed patient care systems in medical institutions is increasing due to COVID-19. In particular, in the case of fluid monitoring, hospitals are considering introducing it as a system that can reduce patient safety and nurses' work. There are two products under development: a load cell method that measures weight and a method that detects drops of sap by infrared sensing. Although each product has differences in operation principle, sensor type, size, usage, and price, medical institutions are highly interested in the accuracy of the data obtained.In this study, two prototypes with different sensor methods were manufactured and the total amount of infusion per hour was measured to test the accuracy, which is the core of the infusion monitoring device. In addition, when there was an external movement, the change in the measured value of the sap was tested to evaluate the accuracy according to the measurement method. As a result of the experiment, there was a difference of less than 5% in the measurement value error of the two devices, and the load cell method showed a difference in the low-capacity measurement value and the infrared method in the high-capacity measurement value. As a result of this experiment, there was little difference in accuracy according to the sensor method of the infusion monitoring device, and it is considered that there is no problem in accuracy when used in a medical institution.

• Journal of Pharmacopuncture
• /
• v.25 no.2
• /
• pp.106-113
• /
• 2022

Objectives: Herbal medicine is a worldwide health topic. Vitex agnus-castus L. (VAC) is a popular plant used for gynecologic problems due to its hormonal effects. The aim of this study is to reveal VAC extract effect on fetus when this herb is used started from antenatal period or during pregnancy. Methods: Performed from starting day of January 2019 till February 2019, 48 rats were assigned in randomly divided eight-member six groups: control (C1), treated group with 365 mg/kg VAC from initiation of insemination (T1) and 30 days prior to pregnancy (T2), control that underwent caesarean section on 15^th day of gestational age (C2) and treated group with 365 mg/kg VAC from initiation of insemination (T3) and 30 days prior to pregnancy (T4) that underwent caesarean section. Weight, sex and number of fetuses, abortion and still birth rate and estradiol level were evaluated using t-test by SPSS software. Results: We showed increased weight among T1 group considering totally and sex-dependent which is significant (all p-value < 0.05). We also detected significantly decreased weight in T2 in total (p-value < 0.0001) and when considering female fetuses (0.043) but not males (0.17). Although the results showed slightly non-significant increased weight among fetuses of T3 (totally or based on the fetus sex) compared to the control group (C2), T4 group had statistically decreased weight compared to control group. Pregnancy rate and pregnancy outcome were affected by VAC usage. The time of VAC initiation also affected live birth and abortion rates. Conclusion: VAC extract may affect pregnancy rate, live birth rate, abortion and stillbirth rates. Its effect on the weight and the sex showed dual pattern depends on the time of initiation and pregnancy trimester of evaluation. Prescribing this medicinal plant for patients being prone to pregnancy should be with caution. Further study is recommended.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.39 no.6
• /
• pp.351-361
• /
• 2021

The seriousness of fire is rising because fire causes enormous damage to property and human life. Therefore, this study aims to predict various risk factors affecting fire by fire type. The predictive analysis of fire factors was carried out targeting Gyeonggi-do, which has the highest number of fires in the country. For the analysis, using machine learning methods SVM (Support Vector Machine), RF (Random Forest), GBRT (Gradient Boosted Regression Tree) the accuracy of each model was presented with a high fit model through MAE (Mean Absolute Error) and RMSE (Root Mean Squared Error), and based on this, predictive analysis of fire factors in Gyeonggi-do was conducted. In addition, using machine learning methods such as SVM (Support Vector Machine), RF (Random Forest), and GBRT (Gradient Boosted Regression Tree), the accuracy of each model was presented with a high-fit model through MAE and RMSE. Predictive analysis of occurrence factors was achieved. Based on this, as a result of comparative analysis of three machine learning methods, the RF method showed a MAE = 1.765 and RMSE = 1.876, as well as the MAE and RMSE verification and test data were very similar with a difference between MAE = 0.046 and RMSE = 0.04 showing the best predictive results. The results of this study are expected to be used as useful data for fire safety management allowing decision makers to identify the sequence of dangers related to the factors affecting the occurrence of fire.

• Journal of Space Technology and Applications
• /
• v.2 no.1
• /
• pp.52-65
• /
• 2022

Korea is near close the success on the indigenous launch vehicle KSLV-2 after the second test launch during the second half of 2022, and the satellite development has been already in the level of advanced country. After the such mature of satellite and launch vehicle technologies, Korea's space development main theme should be 'Space Exploration and Space Application', and paradigm should be changed from 'Hardware' to 'Scientific/Technological Mission', from 'Unmanned' to 'Manned'. Korea's prime space strategy should be the direction of expansion of space industry, creation of employment and secure the key technologies, improvement of convenience and safety of people. For the purpose it is necessary to start 'Manned Space Development' such that participation to 'Artemis and Gateway Program' in 20s' and manned Mars exploration in 30s' which would be carried out by means of global international cooperation, and which could be a good opportunity to explore the new area of space development and upgrade national technology capability. Taking advantage of this opportunity, it is required for Korea to join the international programs through developing indigenous challenging, sustainable Korean mission and hardware. Also selection of the 2^nd Korean Astronaut could draw national attention, especially could give dreams to young generation. Participation to the Artemis program could be the opportunity of entering the major space fairing nation and boosting up national pride. In this study we survey and analyze the Artemis Program in detail, and in conclusion we suggest the strategy of Korea's participation to the Artemis Program.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.1
• /
• pp.81-88
• /
• 2022

In the NRC (New paradigm Reinforced Concrete) beam, steel forms, main angles used as main reinforcements, and shear angles used as basic shear reinforcements are welded and assembled in the form of vierendeel truss structures in a steel factory. After the NRC truss frame is installed at the site, additional main reinforcement and shear reinforcement are distributed. In this study, the shear performance evaluation of the NRC beam was conducted through shear tests in accordance with the type of shear reinforcement of the NRC beam (shear angle, inclined shear reinforcing bar, and U-type cover bar). As a result of the test, the initial stiffness was similar before the initial cracking of each specimen, and all specimens were shear fractured.The shear reinforcements of the specimens exhibited a yielding behavior at the time of the maximum sheat force, and the shear strengths of the specimens increased as the amount of reinforcement of the shear reinforcement increased. These results show that NRC shear reinforcements exhibit shear performance corresponding to their shear strength contribution. As a result of calculating the nominal shear strengths according to KDS 14 20 22, the experimental shear strengths of the NRC beam specimens with shear reinforcement was 37~146% larger than the nominal shear strengths, so It was evaluated as a safety side.

• Nuclear Engineering and Technology
• /
• v.54 no.1
• /
• pp.162-176
• /
• 2022

In Lead-based reactor (LBR) severe accident, the meltdown and migration inside the reactor core will lead to fuel fragment concentration, which may further cause re-criticality and even core disintegration. Accurately predicting the migration and solidification behavior of melt in LBR severe accidents is of prime importance for safety analysis of LBR. In this study, the Moving Particle Semi-implicit (MPS) method is validated and used to simulate the migration and solidification behavior. Two main surface tension models are validated and compared. Meanwhile, the MPS method is validated by the L-plate solidification test. Based on the improved MPS method, the migration and solidification behavior of melt in LBR severe accident was studied furthermore. In the Pb-Bi coolant, the melt flows upward due to density difference. The migration and solidification behavior are greatly affected by the surface tension and viscous resistance varying with enthalpy. The whole movement process can be divided into three stages depending on the change in velocity. The heat transfer of core melt is determined jointly by two heat transfer modes: flow heat transfer and solid conductivity. Generally, the research results indicate that the MPS method has unique advantage in studying the migration and solidification behavior in LBR severe accident.

• Nuclear Engineering and Technology
• /
• v.54 no.2
• /
• pp.479-485
• /
• 2022

At the Korea Institute of Radiological and Medical Sciences, physical human phantoms were developed to evaluate various radiation protection quantities, based on the mesh-type reference computational phantoms of the International Commission on Radiological Protection. The physical human phantoms were fabricated such that a radiophotoluminescent glass dosimeter (RPLGD) with a Tin filter, namely GD-352M, could be inserted into them. A Tin filter is used to eliminate the overestimated signals in low-energy photons below 100 keV. The measurement uncertainty of the RPLGD reader system based on GD-352M should be analyzed for obtaining reliable protection quantities before using it for practical applications. Generally, the measurement uncertainty of RPLGD systems without Tin filters is analyzed for quality assurance of radiotherapy units using a high-energy photon beam. However, in this study, the measurement uncertainty of GD-352M was analyzed for evaluating the protection quantities. The measurement uncertainty factors in the RPLGD include the reference irradiation, regression curve, reproducibility, uniformity, energy dependence, and angular dependence, as described by the International Organization for Standardization (ISO). These factors were calculated using the Guide to the Expression of Uncertainty in Measurement method, applying ISO/ASTM standards 51261(2013), 51707(2015), and SS-ISO 22127(2019). The measurement uncertainties of the RPLGD reader system with a coverage factor of k = 2 were calculated to be 9.26% from 0.005 to 1 Gy and 8.16% from 1 to 10 Gy. A blind test was conducted to validate the RPLGD reader system, which demonstrated that the readout doses included blind doses of 0.1, 1, 2, and 5 Gy. Overall, the E_n values were considered satisfactory.

• Nuclear Engineering and Technology
• /
• v.54 no.7
• /
• pp.2728-2735
• /
• 2022

The research on the flow and heat transfer characteristics of lead bismuth(LBE) is significant for the thermal-hydraulic calculation, safety analysis and practical application of lead-based fast reactors(LFR). In this paper, a new CFD model is proposed to solve the thermal-hydraulic analysis of LBE. The model includes two parts: turbulent model and turbulent Prandtl, which are the important factors for LBE. In order to find the best model, the experiment data and design of 19-pin hexagonal rod bundle with spacer grid, undertaken at the Karlsruhe Liquid Metal Laboratory (KALLA) are used for CFD calculation. Furthermore, the turbulent model includes SST k - 𝜔 and k - 𝜀; the turbulent Prandtl includes Cheng-Tak and constant (Pr_t =1.5,2.0,2.5,3.0). Among them, the combination between SST k - 𝜔 and Cheng-Tak is more suitable for the experiment. But in the low Pe region, the deviation between the experiment data and CFD result is too much. The reason may be the inlet-effect and when Pe is in a low level, the number of molecular thermal diffusion occupies an absolute advantage, and the buoyancy will enhance. In order to test and verify versatility of the model, the NCCL performed by the Nuclear Thermal-hydraulic Laboratory (Nuthel) of Xi'an Jiao tong University is used for CFD to calculate. This paper provides two verification examples for the new universal model.