• Journal of Aerospace System Engineering
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• v.13 no.2
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• pp.26-33
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• 2019

Control moment gyro (CMG) employed as satellite actuators, generates a large torque through the steering of its gimbals. Although each gimbal holds a high-speed rotating wheel, the wheel imbalances induces disturbance and degrades the satellite control quality. Therefore, the disturbances ought to be detected and identified as a precaution against actuator faults. Among the method used in detecting disturbances is the state observers. In this paper, we apply a continuous second order sliding mode observer to detect single disturbances/faults in CMGs. Verification of the algorithm is also done on the hardware satellite simulator where four CMGs are installed.

• East Asian Economic Review
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• v.26 no.1
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• pp.49-91
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• 2022

Recent years have witnessed renewed interest in Africa and public diplomacy has emerged as the vital tool being used to cultivate these relations. China has been leading in pursuing stronger economic partnership with Africa while middle powers such as Korea are also intensifying engagement with the continent. While previous studies have analyzed the implications of China's activities in Africa on advanced powers, none has examined them from the paradigm of middle powers. This study fills this gap by assessing China's activities in Africa, their economic engagement and implications for Korea's interest in Africa. The analysis is qualitative based on secondary data from various sources and literature. The study shows that China's public diplomacy strategy involves a high degree of innovation and has evolved to encompass new tools and audiences. China has institutionalized a cooperative model that permeates many aspects of governance institutions in Africa, enabling it to strengthen their relations. This could also be helping China to adjust faster leadership transitions in Africa. Whereas the US is still the most influential country in Africa, China is influential in economic policies and has outstripped the US in infrastructure diplomacy. This could be because African policy makers align more with China's economic model than the US' mainstream economics. Chinese aid to Africa has been diversified to social sectors that are more responsive to the needs of Africa. Trade and investment relations between China and Africa have deepened, but so does trade imbalance since 2010. China mainly imports natural resources and raw materials from Africa. But this product portfolio is not different from Korea and the US. China's energetic insertion in Africa using various strategies has significant implications for countries with ambitions in Africa. Korea can achieve its ambitions in Africa by focusing resources in areas it can leverage its core strengths-such as education and vocational training, environmental policy and development cooperation.

• Health Policy and Management
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• v.32 no.1
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• pp.73-93
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• 2022

Background: Appropriate physician workforce projection through reasonable discussions and decisions with a broad view on supply and demand of the workforce, thus, is very important for high-quality healthcare services. The study expects to provide preliminary research data on the workforce diagnosis standard model for Korean physician workforce policy decision through more flexible and objective physician workforce projection in reflection of diverse changes in healthcare policy and sociodemographic environments. Methods: A low flow rate through the causal map was developed, and an objective workforce demand projection from 2019 to 2040 was conducted. In addition, projections by scenarios under various situations were conducted with the low flow rate developed in the study. Lastly, the demand projection of the physician workforce by region of 17 cities and provinces was conducted. Results: First, demand of physicians in 2019 was 110,665, 113,450 in 2020, 129,496 in 2025, 146,837 in 2030, 163,719 in 2035, and 179,288 in 2040. Second, the scenario for the retirement of baby boomers led to a decrease in the growth rate due to time delay. Third, Seoul and Gyeonggi-do account for a high percentage of demand, a very high upward trend was identified in Gyeonggi-do, and as a result, the projection showed that the demand of the physician workforce in Gyeonggi-do would worsen over time. Conclusion: This study is meaningful in that rational and collective physician workforce supply and demand and its imbalance in workforce distribution were verified through various projections by scenarios and regions of Korea with System Dynamics.

• Journal of Pharmacopuncture
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• v.25 no.1
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• pp.7-14
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• 2022

Objectives: Some dermatological diseases can be life-threatening. Urticaria and angioedema are common reasons for patients to seek treatment at an emergency department. Severe, generalized urticaria and angioedema can endanger patients' lives by involving the airways and causing anaphylactic shock. The humor-based Persian Medicine (PM) concepts of Shara and Mashara, referring to two kinds of skin lesions, have similarities to urticaria and angioedema, respectively. This article aims to provide scientific evidence regarding the application of PM as an early intervention strategy in the emergency management of urticaria and angioedema. Methods: This was a narrative review of PM studies identified by searching medical databases using search terms related to these diseases, as well as risk-associated keywords such as "fatal", "death", "life-threatening", "emergency", "cupping", and "bloodletting". Data were then compared, interpreted, and analyzed. Results: PM scholars consider the human body as a unified whole and believe in an inner power (Nature) which stems from the body. When the presence of excessive hot substances cause an imbalance of bodily humors, Nature directs their heated vapors sharply toward the skin, thus causing Shara and Mashara. If there is a high risk of inflammation spreading to vital organs under severe conditions, urgent manual interventions are crucial. Conclusion: In serious conditions of urticaria and angioedema, Fasd or bloodletting and Hijama can be effective in speeding up the control of lesions and reducing morbidity and mortality. Consequently, the development of integrated Persian and conventional medicines may provide new therapeutic pathways for skin emergencies.

• Geomechanics and Engineering
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• v.29 no.3
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• pp.291-300
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• 2022

Tunnel boring machines combined with the earth pressure balanced shield method (EPB shield TBMs) have been adopted in urban areas as they allow excavation of tunnels with limited ground deformation through continuous and repetitive excavation and support. Nevertheless, the expansion of TBM construction requires much more minor and exquisitely controlled surface settlement to prevent economic loss. Several parametric studies controlling the tunnel's geometry, ground properties, and TBM operational factors assuming ordinary conditions for EPB shield TBM excavation have been conducted, but the impact of excessive excavation on the induced settlement has not been adequately studied. This study conducted a numerical evaluation of surface settlement induced by the ground loss from face imbalance, excessive excavation, and tail void grouting. The numerical model was constructed using FLAC3D and validated by comparing its result with the field data from literature. Then, parametric studies were conducted by controlling the ground stiffness, face pressure, tail void grouting pressure, and additional volume of muck discharge. As a result, the contribution of these operational factors to the surface settlement appeared differently depending on the ground stiffness. Except for the ground stiffness as the dominant factor, the order of variation of surface settlement was investigated, and the volume of additional muck discharge was found to be the largest, followed by the face pressure and tail void grouting pressure. The results from this study are expected to contribute to the development of settlement prediction models and understanding the surface settlement behavior induced by TBM excavation.

• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.148-163
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• 2021

Timely fault identification is important for safe and reliable operation of the electric valve system. Many research works have utilized different data-driven approach for fault diagnosis in complex systems. However, they do not consider specific characteristics of critical control components such as electric valves. This work presents an integrated shallow-deep fault diagnostic model, developed based on signals extracted from DN50 electric valve. First, the local optimal issue of particle swarm optimization algorithm is solved by optimizing the weight search capability, the particle speed, and position update strategy. Then, to develop a shallow diagnostic model, the modified particle swarm algorithm is combined with support vector machine to form a hybrid improved particle swarm-support vector machine (IPs-SVM). To decouple the influence of the background noise, the wavelet packet transform method is used to reconstruct the vibration signal. Thereafter, the IPs-SVM is used to classify phase imbalance and damaged valve faults, and the performance was evaluated against other models developed using the conventional SVM and particle swarm optimized SVM. Secondly, three different deep belief network (DBN) models are developed, using different acoustic signal structures: raw signal, wavelet transformed signal and time-series (sequential) signal. The models are developed to estimate internal leakage sizes in the electric valve. The predictive performance of the DBN and the evaluation results of the proposed IPs-SVM are also presented in this paper.

• Nuclear Engineering and Technology
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• v.52 no.12
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• pp.2743-2759
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• 2020

A detailed computational fluid dynamics (CFD) simulation analysis model was developed using ANSYS CFX 16.1 and analyzed to simulate the basic design and internal flow characteristics of a 180 MW small modular reactor (SMR) with a natural circulation flow system. To analyze the natural circulation phenomena without a pump for the initial flow generation inside the reactor, the flow characteristics were evaluated for each output assuming various initial powers relative to the critical condition. The eddy phenomenon and the flow imbalance phenomenon at each output were confirmed, and a flow leveling structure under the core was proposed for an optimization of the internal natural circulation flow. In the steady-state analysis, the temperature distribution and heat transfer speed at each position considering an increase in the output power of the core were calculated, and the conceptual design of the SMR had a sufficient thermal margin (31.4 K). A transient model with the output ranging from 0% to 100% was analyzed, and the obtained values were close to the T_hot and T_cold temperature difference value estimated in the conceptual design of the SMR. The K-factor was calculated from the flow analysis data of the CFX model and applied to an analysis model in RELAP5/MOD3.3, the optimal analysis system code for nuclear power plants. The CFX analysis results and RELAP analysis results were evaluated in terms of the internal flow characteristics per core output. The two codes, which model the same nuclear power plant, have different flow analysis schemes but can be used complementarily. In particular, it will be useful to carry out detailed studies of the timing of the steam generator intervention when an SMR is activated. The thermal and hydraulic characteristics of the models that applied porous media to the core & steam generators and the models that embodied the entire detail shape were compared and analyzed. Although there were differences in the ability to analyze detailed flow characteristics at some low powers, it was confirmed that there was no significant difference in the thermal hydraulic characteristics' analysis of the SMR system's conceptual design.

• Journal of Digital Policy
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• v.1 no.2
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• pp.17-24
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• 2022

In China, the continuous promotion and coverage of scanning code payment has caused an imbalance in the coin market. Coin changers can not only alleviate this problem, but also affect the business development of commercial banks. Therefore, it is meaningful to study the coin changer. The purpose of this paper is to study the impact of coin changers on the business of commercial banks in China. Through on-the-spot visits and based on the manually collected customer data of Chinese commercial banks as the object, combined with the calculation method of financial indicators to conduct case analysis. The results of the study show that the coin changer has a positive impact on the business development of Chinese commercial banks. This paper provides feasible suggestions and new ideas for business development to Chinese commercial banks. At present, there are few related studies on coin exchange machines. This study combines the calculation of financial indicators to verify the policy results, which is the innovation of this study.

• The Journal of the Convergence on Culture Technology
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• v.8 no.6
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• pp.861-866
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• 2022

Seoul introduced the shared bicycle system, "Seoul Public Bike" in 2015 to help reduce traffic volume and air pollution. Hence, to solve various problems according to the supply and demand of the shared bicycle system, "Seoul Public Bike," several studies are being conducted. Most of the research is a strategic "Bicycle Rearrangement" in regard to the imbalance between supply and demand. Moreover, most of these studies predict demand by grouping features such as weather or season. In previous studies, demand was predicted by time-series-analysis. However, recently, studies that predict demand using deep learning or machine learning are emerging. In this paper, we can show that demand prediction can be made a little better by discovering new features or ordering the importance of various features based on well-known feature-patterns. In this study, by ordering the selection of new features or the importance of the features, a better coefficient of determination can be obtained even if the well-known deep learning or machine learning or time-series-analysis is exploited as it is. Therefore, we could be a better one for demand prediction.

• Journal of the Korean Dietetic Association
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• v.28 no.4
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• pp.227-246
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• 2022

This study was conducted on the nutritional status of 1,805 patients with allergic diseases (atopic dermatitis, allergic rhinitis, and asthma) aged 19 to 64 years according to their state of depression, based on the data from the Korea National Health and Nutrition Examination Survey (KNHANES). The Patient Health Questionnaire-9 (PHQ-9) was used to diagnose depression. Subjects with a score of 10 or more were categorized into the depression group (n=152) and the rest into the non-depression group (n=1,653). The results of this study were as follows: The proportion of women (75.7%) was higher than that of men (24.3%) in the depressed group (P<0.01). In terms of energy intake per 1,000 kcal, both men and women in the depressed group showed a lower energy intake than the non-depressed group and this intake was less than the estimated energy requirement (EER). The nutrient intakes of protein, calcium, phosphorus, iron, vitamin A, thiamine, riboflavin, niacin, folic acid, and vitamin C were below the estimated average requirement (EAR). Also, the intakes of fiber and potassium were less than the adequate intake (AI) (P<0.001). In the lifestyle parameters, the ratio of eating alone at lunch was 54.1%:33.1%, indicating that more than half of the depression group ate alone. In conclusion, it was observed that the nutritional status of allergic disease patients was imbalanced. The nutritional imbalance was due to insufficient energy intake and inadequate intake of nutrients, which was below the average requirements of vitamins and minerals and this was more evident in the depression group than in the non-depression group.