• Progress in Superconductivity and Cryogenics
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• v.25 no.3
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• pp.49-55
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• 2023

This paper presents the design of a re-liquefaction system as a BOG (boil-off gas) handling process in liquid hydrogen transport vessels. The total capacity of the re-liquefaction system was assumed to be 3 ton/day, with a BOR (boil-off rate) of 0.2 %/day inside the cargo. The re-liquefaction cycle was devised using the He-Brayton Cycle, incorporating considerations of BOG capacity and operational stability. The primary components of the system, such as compressors, expanders, and heat exchangers, were selected to meet domestically available specifications. Case studies were conducted based on the specifications of the components to determine the optimal design parameters for the re-liquefaction system. This encompassed variables such as helium mass flow rate, the number of compressors, compressor inlet pressure and compression ratio, as well as the quantity and composition of expanders. Additionally, an analysis of exergy destruction and exergy efficiency was carried out for the components within the system. Remarkably, while previous design studies of BOG re-liquefaction systems for liquid hydrogen vessels were confined to theoretical and analytical realms, this research distinguishes itself by accounting for practical implementation through equipment and system design.

• The Journal of Korean Academic Society of Nursing Education
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• v.30 no.1
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• pp.29-38
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• 2024

Purpose: This study aimed to investigate student nurses' satisfaction by type of clinical practicum and to determine predictors of clinical competence in pediatric nursing. Methods: A total of 189 Junior and Senior student nurses across seven colleges in the Busan Metropolitan City were enrolled in the study. The participants completed a structured questionnaire containing items about their learning satisfaction with different types of pediatric nursing practicums and their clinical competence. Data were analyzed using the mean, standard deviation, independent t-test, ANOVA, and multiple regression analysis. Results: Regarding satisfaction with each type of clinical practicum, the mean satisfaction score (out of 10) was 8.18±2.26 for on-site clinical rotations and 7.35±2.20 for alternative practicums. Among the different types of alternative practicum approaches, those with a satisfaction score of 7 or higher included fundamental nursing skills, watching videos, simulation etc., while those with a satisfaction score of less than 6 were virtual simulation and problem-based learning. The predictors of clinical competence in pediatric nursing were learning satisfaction with practice, school year, and alternative practicum, accounting for 35.0% of the variance in clinical competency. Conclusion: It would be helpful to combine on-site clinical rotations with alternative practicum approaches and to develop various alternative practice programs using simulation practice, virtual reality, immersive interactive systems, and standardized patients to enhance students' clinical competency.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.2
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• pp.189-197
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• 2024

Galileo is a European Global Navigation Satellite System (GNSS) that has offered the Galileo Open Service since 2016. Consequently, the standardization of GNSS augmentation systems, such as Satellite Based Augmentation System (SBAS), Ground Based Augmentation System (GBAS), and Aircraft Based Augmentation System (ABAS) for Galileo signals, is ongoing. In 2023, the European Union Space Programme Agency (EUSPA) released prior probabilities of a satellite fault and a constellation fault for Galileo, which are 3×10^-5 and 2×10^-4 per hour, respectively. In particular, the prior probability of a Galileo constellation fault is significantly higher than that for the GPS constellation fault, which is defined as 1×10^-8 per hour. This raised concerns about its potential impact on GBAS integrity monitoring. According to the Global Positioning System (GPS) Standard Positioning Service Performance Standard (SPS PS), a constellation fault is classified as a wide fault. A wide fault refers to a fault that affects more than two satellites due to a common cause. Such a fault can be caused by a failure in the Earth Orientation Parameter (EOP). The EOP is used when transforming the inertial axis, on which the orbit determination is based, to Earth Centered Earth Fixed (ECEF) axis, accounting for the irregularities in the rotation of the Earth. Therefore, a faulty EOP can introduce errors when computing a satellite position with respect to the ECEF axis. In GNSS, the ephemeris parameters are estimated based on the positions of satellites and are transmitted to navigation satellites. Subsequently, these ephemeris parameters are broadcasted via the navigation message to users. Therefore, a faulty EOP results in erroneous broadcast ephemeris data. In this paper, we assess the conventional ephemeris fault detection monitor currently employed in GBAS for wide faults, as current GBAS considers only single failure cases. In addition to the existing requirements defined in the standards on the Probability of Missed Detection (PMD), we derive a new PMD requirement tailored for a wide fault. The compliance of the current ephemeris monitor to the derived requirement is evaluated through a simulation. Our findings confirm that the conventional monitor meets the requirement even for wide fault scenarios.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.20 no.1
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• pp.1-6
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• 2024

Crud is a corrosion deposit that forms in equipments and piping of nuclear reactor's primary systems. When crud circulates through the reactor's primary system coolant and adheres to the surface of the nuclear fuel cladding tube, it can lead to the Axial Offset Anomaly (AOA) phenomenon. This occurrence is known to potentially reduce the output of a nuclear power plant or to necessitate an early shutdown. Consequently, worldwide nuclear power plants have employed ultrasonic cleaning methods since 2000 to mitigate crud deposition, ensuring stable operation and economic efficiency. This paper details the system configuration of ultrasonic nuclear fuel cleaning equipment, outlining the function of each component. The objective is to contribute to the local domestic production of ultrasonic nuclear fuel cleaning equipment. Additionally, the paper introduces a method for accurately measuring the weight of removed crud, a crucial factor in assessing cleaning effectiveness and providing input data for the BOA code used in core safety evaluations. Accurate measurement of highly radioactive filters containing crud is essential, and weighing them underwater is a common practice. However, the buoyancy effect during underwater weighing may lead to an overestimation of the collected crud's weight. To address this issue, the paper proposes a formula correcting for buoyancy errors, enhancing measurement accuracy. This improved weight measurement method, accounting for buoyancy effects in water, is expected to facilitate the quantitative assessment of filter weights generated during chemical decontamination and system operations in nuclear power plants.

• International Journal of Computer Science & Network Security
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• v.24 no.1
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• pp.95-106
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• 2024

The article is devoted to the design and development of an information system for preserving the results of testing to verify the residual knowledge of students of the resource for training specialists in information and communication technologies. The purpose of the study is to provide a scientific justification for the problem of developing professional training of specialists in information and communication technologies in the process of using an information system to save test results to verify students' residual knowledge and to verify the effectiveness of its implementation in universities. According to the results of the experiment, it can be argued that the introduction of an information system to preserve the results of testing to test students' residual knowledge in the educational process contributes to the professional training of specialists in information and communication technologies at the universities of Ukraine. The practice of development and use of modern information technologies focused on the implementation of psychological and pedagogical goals of teaching and education is fundamentally new mediated by modern technical and technological innovations.

• Korean Journal of Radiology
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• v.20 no.5
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• pp.823-829
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• 2019

Objective: To summarize the high-resolution computed tomography (HRCT) and magnetic resonance imaging (HRMRI) features of duplicated internal auditory canals (DIACs). Materials and Methods: Ear HRCT data of 64813 patients with sensorineural hearing loss (SNHL), obtained between August 2009 and November 2017, were reviewed. Among these patients, 12 (13 ears) were found to have DIACs, 9 of whom underwent HRMRI. Their images were evaluated by two otoradiologists. Results: The rate of occurrence of DIAC among SNHL patients was 0.019% (12/64813). The internal auditory canals of 13 ears were divided into double canals by complete (n = 6) and incomplete (n = 7) bony septa, with varied orientations ranging from horizontal to approximately vertical. All of the anterosuperior canals extended into the facial nerve (FN) canal, except for 1, which also extended to the vestibule. The posteroinferior canals ended in the cochlea and vestibule, except for 2, which also connected to the FN canals. Magnetic resonance images revealed that 77.8% (7/9) and 22.2% (2/9) of vestibulocochlear nerves (VCNs) were aplastic and hypoplastic, respectively. Furthermore, 88.9% (8/9) of FNs were normal, except for 1, which was hypoplastic. All of the affected ears also had other ear anomalies: a narrow, bony cochlear nerve canal was the most common other anomaly, accounting for 92.3% (12/13). Malformations of other systems were not found. Conclusion: Double-canal appearance is a characteristic finding of DIAC on HRCT, and it is usually accompanied by other ear anomalies. The VCN usually appears aplastic, with a normal FN, on HRMRI.

• Journal of Information Processing Systems
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• v.20 no.3
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• pp.391-398
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• 2024

Given the further promotion of economic globalization, China's financial market has also expanded. However, at present, this market faces substantial risks. The main financial and economic risks in China are in the areas of policy, credit, exchange rates, accounting, and interest rates. The current status of China's financial market is as follows: insufficient attention from upper management; insufficient innovation in the development of the financial economy; and lack of a sound financial and economic risk protection system. To further understand the current situation of China's financial market, we conducted a questionnaire survey on the financial market and reached the following conclusions. A comprehensive enterprise questionnaire from the government's perspective, the enterprise's perspective and the individual's perspective showed that the following problems exist in the financial and economic risk prevention aspects of big data and Internet of Things in China. The political system at the country's grassroots level is not comprehensive enough. The legal regulatory system is not comprehensive enough, leading to serious incidents of loan fraud. The top management of enterprises does not pay enough attention to financial risk prevention. Therefore, we constructed a financial and economic risk prevention model based on big data and Internet of Things that has effective preventive capabilities for both enterprises and individuals. The concept reflected in the model is to obtain data through Internet of Things, use big data for screening, and then pass these data to the big data analysis system at the grassroots level for analysis. The data initially screened as big data are analyzed in depth, and we obtain the original data that can be used to make decisions. Finally, we put forward the corresponding opinions, and their main contents represent the following points: the key is to build a sound national financial and economic risk prevention and assessment system, the guarantee is to strengthen the supervision of national financial risks, and the purpose is to promote the marketization of financial interest rates.

• The Journal of Korean Medicine
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• v.45 no.3
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• pp.54-64
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• 2024

Objectives: Tonifying herbal medicines are used to nourish and balance the body's qi, blood, yin, and yang, targeting deficiencies. They are the second most frequently used category by consumers visiting Korean medicine clinics, following prescriptions for back pain. This study aimed to analyze the adverse events associated with herbal medicine products classified as tonics through a national pharmacovigilance database. Methods: We investigated 11 types of tonifying herbal medicine products (466 product codes) in the Korea Adverse Event Reporting System (KAERS) database from 2012 to 2021. Extracted adverse event reports were analyzed based on information of reports, patient demographics, classification of adverse events, reported herbal medicine products, and causality assessment results. Results: A total of 31 individual case safety reports were identified, covering 33 adverse events. The annual number of reports has increased over the study period. Most reports were filed by physicians and pharmacists, with the majority of patients being adults or elderly. Gastrointestinal disorders were the most frequently reported adverse events, accounting for 48.5% of cases. Of the 33 adverse events, 93.9% were classified as non-serious, while 6.1% were classified as serious. The most frequently reported herbal medicine products were Bojungikgi-tang, Yukmijihwang-tang, and Palmijihwang-tang. Conclusions: Although the study found that adverse events associated with tonifying herbal medicine products are generally not serious, it highlights the importance of systematic monitoring and reporting. The findings underscore the need for improved adverse event reporting systems within traditional Korean medicine to ensure patient safety and guide future research.

• Journal of Bio-Environment Control
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• v.31 no.3
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• pp.246-254
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• 2022

Domestic facility agriculture grows rapidly, such as modernization and large-scale. And the production scale increases significantly compared to the area, accounting for about 60% of the total agricultural production. Greenhouses require energy input to create an appropriate environment for stable mass production throughout the year, but the energy load per unit area is large because of low insulation properties. Through the rooftop greenhouse, one of the types of urban agriculture, energy that is not discarded or utilized in the building can be used in the rooftop greenhouse. And the cooling and heating load of the building can be reduced through optimal greenhouse operation. Dynamic energy analysis for various environmental conditions should be preceded for efficient operation of rooftop greenhouses, and about 40% of the solar energy introduced in the greenhouse is energy exchange for crops, so it should be considered essential. A major analysis is needed for each sensible heat and latent heat load by leaf surface temperature and evapotranspiration, dominant in energy flow. Therefore, an experiment was conducted in a rooftop greenhouse located at the Korea Institute of Machinery and Materials to analyze the energy exchange according to the growth stage of crops. A micro-meteorological and nutrient solution environment and growth survey were conducted around the crops. Finally, a regression model of leaf temperature and evapotranspiration according to the growth stage of leafy vegetables was developed, and using this, the dynamic energy model of the rooftop greenhouse considering heat transfer between crops and the surrounding air can be analyzed.

• Management & Information Systems Review
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• v.36 no.1
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• pp.233-249
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• 2017

This study investigates the relation of managerial ability and firm performance in case of Chaebol in Korea. We employ non-financing firms at Korean markets for the period 2000-2015. Most important decision is made by the head of Chaebol which increases firm value eventually and he has such a strong dominant power that managers belongs to Chaebol have to follow mother firm's decision directions. So it is expected that managers belongs to Chaebol have to focus on long term performance rather than short term profits, which means they concentrate their managerial ability much on the firm value. Otherwise, managers in which non-Chaebol focus their ability on periodic accounting earnings. Thus, this study examines an empirical analysis on the relation of managerial ability and firm performance and the effect of Chaebol on the relation of managerial ability and firm performance. Empirical results are as follows: First, there exists a statistically significant positive relation between managerial ability and firm performance either short- or long-term. Second, we extend this relationship into Chaebol condition and find that managerial ability of Chaebol positively influences on the firm value which is long-term performance, rather than return on assets which is short-term performance. These results imply that managers belongs to Chaebol much concentrate their ability on long-term value which is differenciated from the case of non-Chaebol samples. Chaebol is an important issue in Korea because it dominates most of Korean local economy so its' impact from small changes on our economy is big enough. Our study examining the relationships between managerial ability of Chaebol and firm performance is meaningful and it is a good signal that they concentrate their ability much on the long-term value rather than short-term profits. We expect that the results of this study will provide the academic and practical references. This study will contribute to the future research in accounting through an analysis of managerial ability which is a new measure, Chaebol, and firm value.