• Nuclear Engineering and Technology
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• v.17 no.1
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• pp.34-44
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• 1985

The main purpose of this work is to study the effects of (1) configuration, size, and materials of electrodes, (2) flow pattern, (3) electrode position with respect to a dielectric boundary on the void fraction measurement and flow regime characterization by capacitance transducers. From the experimental results, relationships between the measured relative capacitance and void fraction are obtained for both annular and stratified flow systems under static condition, and this result is compared with theoretical predictions. From this study it can be concluded that (1) the strip-type electrodes are more sensitive than ring-type electrodes for both annular and stratified flows, (2) electrode size does not affect the relative capacitance vs. (1-$\alpha$) curve, and (3) electrode position is important for stratified flows but it has no effect on annular flows.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.869-877
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• 2020

A 24-month Advanced Power Reactor 1400 (APR1400) core with a very-low-boron (VLB) concentration has been investigated for an inherently safe and high-performance PWR in this work. To develop a high-performance APR1400 which is able to do the passive frequency control operation, VLB feature is essential. In this paper, the centrally-shielded burnable absorber (CSBA) is utilized for an efficient VLB operation in the 24-month cycle APR1400 core. This innovative design of the VLB APR1400 core includes the optimization of burnable absorber and loading pattern as well as axial cutback for a 24-month cycle operation. In addition to CSBA, an Er-doped guide thimble is also introduced for partial management of the excess reactivity and local peaking factor. To improve the neutron economy of the core, two alternative radial reflectors are adopted in this study, which are SS-304 and ZrO₂. The core reactivity and power distributions for a 2-batch equilibrium cycle are analyzed and compared for each reflector design. Numerical results show that a VLB core can be successfully designed with 24-month cycle and the cycle length is improved significantly with the alternative reflectors. The neutronic analyses are performed using the Monte Carlo Serpent code and 3-D diffusion code COREDAX-2 with the ENDF/B-VII.1.

• Journal of Korea Water Resources Association
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• v.54 no.10
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• pp.759-768
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• 2021

This work introduces a new approach that classifies individual household water usage by examining the characteristics of smart meter end-user demand data. Here, one of the most well-known unsupervised machine learning, K-means algorithm, is applied to classify water consumptions by each household. The intensity and duration of end-user demands are used as main features to determine the households with similar water consumption pattern. The results showed that 21 households are classified into 13 clusters with each cluster having one, two, three, or five houses. The reasoning why multiple households are classified into the same cluster is described in this paper with respect to the collected data and end-user water consumption behavior.

• Nuclear Engineering and Technology
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• v.53 no.7
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• pp.2207-2220
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• 2021

Lead alloy is used as coolant in Lead-based cooled Fast Reactor (LFR). The natural characteristics of lead alloy are combined with the simple structural design of LFR. This constitutes the inherent safety characteristics of LFR. The main work of this paper is to take the main coolant pump (MCP) in the lead-cooled fast reactor (LFR) as the research object, and to study the flow pattern distribution of the internal flow field under the reverse rotation pump condition, the reverse rotation positive-flow braking condition and the reverse rotation negative-flow braking condition. In this paper, the double-outlet volute type and the space guide vane are selected as the potential designs of the CLEAR-I MCP. In this paper, the CFD method is used to study the potential reverse accident of the MCP. It is found that the highest flow velocity in the impeller appears at the impeller outlet, and the Q-H curves of the two design programs basically coincide. The space guide vane type MCP has better hydraulic performance under the reverse rotation positive-flow condition, the Q-H curves of the two designs gradually separate with increasing flow rate, and the maximum flow velocity inside the space guide vane type MCP is obviously lower than that of the double-outlet volute type. For the reverse rotation test of MCP, only the condition of the forward rotating pump of the main coolant pump is tested and verified. For the simulation of the MCP in LBE medium, it proved that the turbulence model and basic settings selected in the simulation are reliable.

• Journal of the Korea Convergence Society
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• v.12 no.12
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• pp.551-562
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• 2021

This study aimed to identify the effect of resilience and positive psychological capital on hospital nurses' professional quality of life. A cross-sectional survey design was utilized to investigate 221 general hospital nurses from June 1 to 30, 2021. Professional quality of life (ProQOL), which is conceptualized with three sub-dimensions (compassion satisfaction, burnout, and secondary traumatic stress), resilience, and positive psychological capital variables were measured. There was a positive relationship between compassion satisfaction and resilience, positive psychological capital, and a negative relationship among burnout, secondary traumatic stress, and the other variables in this study. The main factors influencing compassion satisfaction were resilience, and positive psychological capital, which explained about 47% of compassion satisfaction. Burnout was influenced by resilience, positive psychological capital, and work pattern, and these variables explained about 37% of burnout. Notably, it was found that resilience was the most crucial factor in nurses' compassion satisfaction, and positive psychological capital was the most crucial factor in nurses' burnout. Thus, it is suggested to develop and verify the effectiveness of a resilience improvement program and positive psychological intervention program to strengthen the internal resources of hospital nurses.

• 한국사회정책
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• v.25 no.4
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• pp.199-231
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• 2018

The development of ICT has led to changes in the pattern and the meaning of work and requires restructuring of the existing social security system, which was established chiefly for the wage workers in the industrial economy. However, while economic activities within the digital platform markets are different from industrial labour, there is still a lack of discussion on what social problems platform workers can face and how to cope with them. As a comprehensive sketch of economic activities in platform economy, this study identifies the types of platform workers and analyses three characteristics of their economic activities - flexibility, virtuality, and connectivity. It then examines what social risks can be derived form the three characteristics. This research lastly suggests alternative social safety nets and policies to alleviates the social risks and problems that platform workers may face in the digital society.

• Korean Journal of Labor Studies
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• v.24 no.3
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• pp.73-107
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• 2018

The purpose of this study is to shed light on the characteristics of the social relations of migrant workers in the Ansan area and the factors for the construction of those characteristics. The social relations of migrant workers in the Ansan area are affected by the Korean government's policy of EPS, a short-term rotation policy and its ban on the settlement of migrant workers. These workers are likely to form a temporary and bounded social relationship. The bounded social relationship of migrant workers to society is one of the major factors that put them in social poverty. Ethnic communities, support organizations for migrant workers, and local government agencies have assumed the task of helping build the network among migrant workers of various ethnic backgrounds as well as aiding their participation in local social activities. The status of a temporary resident is the prime reason for spatial exclusion and social poverty among migrant workers. To prevent the exacerbation of these phenomena, this study suggests that the government reconsider its short-term work permit policy for less skilled workers.

• Journal of Internet Computing and Services
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• v.20 no.3
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• pp.77-84
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• 2019

Workflow management system is a system that manages the workflow model which defines the process of work in reality. We can define the workflow process by sequencing jobs which is performed by the performers. Using the workflow management system, we can also analyze the flow of the process and revise it more efficiently. Many researches are focused on how to make the workflow process model more efficiently and manage it more easily. Recently, many researches use the workflow log files which are the execution history of the workflow process model performed by the workflow management system. Ourresearch group has many interests in making useful knowledge from the workflow event logs. In this paper we use XES log files because there are many data using this format. This papersuggests what are the cardinalities of the temporal workcases and how to get them from the workflow event logs. Cardinalities of the temporal workcases are the occurrence pattern of critical elements in the workflow process. We discover instance cardinalities, activity cardinalities and organizational resource cardinalities from several XES-based workflow event logs and visualize them. The instance cardinality defines the occurrence of the workflow process instances, the activity cardinality defines the occurrence of the activities and the organizational cardinality defines the occurrence of the organizational resources. From them, we expect to get many useful knowledge such as a patterns of the control flow of the process, frequently executed events, frequently working performer and etc. In further, we even expect to predict the original process model by only using the workflow event logs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.1
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• pp.45-53
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• 2019

As the urbanization progresses, the demand for parking in large cities surges compared with that for parking lots. However, the space for securing a parking lot in a large city is physically limited and a budget problem also arises. Therefore, a shared parking system that can utilize existing parking lots is becoming important. This study was carried out to analyze the parking area efficiently for the residents parking area. As a result of the questionnaire survey, it was the most frequent passage to work / commuting and business purposes. The most important factors in parking were 'Parking charge', 'Walking distance to the destination after parking', 'Parking lot searching time' Approximately 46 % of the respondents were female. As a result of the quantitative analysis of the factors influencing the potential use of the intention to use as a dependent variable, it was analyzed that the policy was effective to reduce the parking fee to less than 500 won per 10 minutes and take about 3-6 minutes to search.

• Journal of the Korean GEO-environmental Society
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• v.20 no.3
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• pp.5-14
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• 2019

This study attempted to study the soil erosion dynamic in the Bagmati Basin of Nepal. In this study, an inclusive methodology that combines Revised Universal Soil Loss Equation (RUSLE) and GIS techniques was adopted to determine the distribution of soil loss in the study basin. As well, this study attempts to study the intensity of soil erosion in the seven different land use patterns in the Bagmati Basin. Soil loss is an associated phenomenon of hydrologic cycle and this dynamic phenomenon possesses threats to sustainability of basin hydrology, agriculture system, hydraulic structures in operation and overall ecosystem in a long run. Soil conservation works, and various planning and design of watersheds works demands quantification of soil loss. The results of the study in Bagmati Basin shows the total annual soil loss in the basin is 22.93 million tons with an average rate of 75.83T/ha/yr. The computed soil loss risk was divided into five classes from tolerable to severe and the spatial pattern was mapped for easy interpretation. Also, evaluation of soil loss in different land use categories shows barren area has highest rate of soil loss followed by agriculture area. This is a preliminary work and provides erosion risk scenario in the basin. The study can be further used for strategic planning of land use and hydrologic conservation works in a basin.